In this chapter, we first present some general characteristics of
the passive and then a movement analysis of it. Although superficially
the passive does not resemble subject raising, our analysis of it treats
the two constructions as analogous in certain respects. Moreover,
subject raising turns out to be analogous not just to the passive of
simple clauses, but also to the passive of complex clauses containing
ECM verbs. All three phenomena (simple passive, passive with ECM verbs,
subject raising) turn out to obey a correlation
called Burzio's generalization,
according to which verbs that lack an agent argument also lack the
ability to check case. We show further that there are two
types of case, structural and inherent, and that Burzio's generalization
holds only for structural case. Finally, we discuss the passive of
double object sentences in English on the one hand and in German and
Latin on the other.
Characteristics of the passive
In English, as in most other languages, active sentences like (1a)
have passive counterparts like (1b).
| (1) | a. | Active | Nancy | approved | them. | ||
| Thematic role | Agent | Theme | |||||
| Grammatical relation | Subject | Direct object | |||||
| b. | Passive | They | were approved | (by | Nancy). | ||
| Thematic role | Theme | Agent | |||||
| Grammatical relation | Subject | Object of preposition | |||||
Passivization has a number of effects. First and foremost, the agent argument, which is expressed as the subject of the active sentence, appears in the passive as an optional by phrase. Second, the now vacant subject position is taken over by the theme argument. In other words, the agent and theme arguments are linked to different grammatical relations in the passive than in the active. If subject and object are ranked as higher and lower on a hierarchical scale of grammatical relations, as is often done, the passive demotes the agent argument and promotes the theme argument. Third, passive past participle, unlike their homonymous active counterparts, can't check objective case.
| (2) | a. | Active | Nancy has approved them. | |
| b. | Passive | * | { Itexpl, Thereexpl } was approved them. | |
| Intended meaning: 'They were approved.' | ||||
| Inchoative manner-of-motion verbs
are not passive verbs.
It is true that sentences like (i) share with passives the property that their subject is a theme, rather than an agent. However, they differ from passives in not allowing the expression of an agent, as shown in (ii).1
|
In English, the passive is expressed analytically by a combination of the past participle and an auxiliary verb (be or get). Other languages allow the passive to be expressed synthetically, as illustrated in (3) for Korean and in (4) for Latin.
| (3) | a. | Active | Chulswu-ka kyehoyk-ul helak- ha- yessta. Chulswu nom plans acc approve active past Agent Theme Subject Direct object 'Chulswu approved the plans.' | |
| b. | Passive | Kyehoyk-i (chulswu-eyuyhaye) helak- toy- essta. plans nom Chulswu by approve passive past Theme Agent Subject Object of postposition 'The plans were approved (by Chulswu).' | ||
| (4) | a. | Active | Puer-i port-am claud-unt. boy nom.pl.m door acc.sg.f close 3.pl.pres Agent Theme Subject Direct object 'The boys are closing the door.' | |
| b. | Passive | Port-a (a puer-is) claud-it- ur. door nom.sg.f by boy abl.pl.m close 3.sg.pres passive Theme Agent Subject Object of preposition 'The door is being closed (by the boys).' |
In these languages, it is the bound morphemes -toy- and -ur that result in the effects of passivization mentioned above. As in English, the grammatical relations of the agent and theme arguments differ in the active and the passive, and passive verb forms cannot check the case that active verb forms can.
| (5) | a. | * | Kyehoyk-ul (chulswu-eyuyhaye) helak- toy- essta. plans acc Chulswu by approve passive past Intended meaning: 'The plans were approved (by Chulswu).' | |
| b. | * | Port-am (a puer-is) claud-it- ur. door acc.sg.f. by boy abl.pl.m. close 3.sg.pres passive Intended meaning: 'The door is being closed by the boys.' |
Latin (among other languages) also uses the analytic strategy for the passive in certain linguistic contexts. In particular, the passive voice in the present perfect, past perfect, and future perfect perfect is formed by combining the passive participle with the appropriate form of esse 'be', as illustrated in (6).
| (6) |
Port-a (a puer-is) claus- a { est, erat, erit } .
door nom.sg.f by boy abl.pl.m close.part.pass nom.sg.f is was will.be
Theme Agent
Subject Object of preposition
'The door { has, had, will have } been closed (by the boys).'
|
It is worth noting that the synthetic passive form in (4b) agrees
with the subject in case and number, but that the participle in the
analytic form in (6) shows additional gender agreement. Gender is
ordinarily a feature of the nominal system (nouns and their canonical
modifiers, adjectives), so participles share features of both verbs and
adjectives. Indeed, the term 'participle' implies as much, as it
derives from Latin particeps 'sharing'.
A movement analysis of the passive
Object idiom chunks
In addition to the subject idiom chunks discussed in
| (7) | a. | They are making some headway on a solution. | |
| b. | They will | ||
| c. | She took little note of what I said. | ||
| d. | The government keeps close tabs on his operations. |
The restriction of object idiom chunks to the complement position of the licensing verb is thrown into striking relief by the contrast between nearly synonymous expressions such as attention and heed, or progress and headway (Radford 1988:423). The variants with the ordinary expressions (attention, progress) are fine, but those with the idiom chunks (heed, headway) are not since they are not licensed by the verbs in red.
| (8) | a. | Please be prepared to report some
| |
| b. | We appreciate your | ||
| (9) | a. | He's always trying to attract my
| |
| b. | He's a child who requires a lot of
|
Given their licensing requirements, it isn't surprising that object idiom chunks are generally ungrammatical in subject position.
| (10) | a. | ||
| b. | More | ||
| c. |
They are, however, able to occur in subject position under one condition - in passive sentences where the passive participle is that of the licensing verb. This is illustrated by the contrast between (11) and (12) (Radford 1988:423).
| (11) | a. | Some headway is being made on a solution. | |
| b. | Little heed was paid to her proposal. | ||
| c. | Due homage was paid to the dead. | ||
| d. | Little note was taken of what I said. | ||
| e. | Close tabs were kept on his operations. | ||
| (12) | a. | * | My heed was attracted immediately. |
| b. | * | Your close heed is required. | |
| c. | * | A bit of headway was reported at the meeting. | |
| d. | * | Our headway in solving the problem wasn't sufficiently appreciated. |
As we have just seen, object idiom chunks in active sentences are locally licensed as well - namely, as the complements of a licensing verb, and this local relationship is extended in passive sentences. In other words, although the licensing relationship differs in both cases (spec-predicate for subject raising, head-comp for passive), the passive is analogous to subject raising in that both constructions superficially extend a local licensing relationship. This fundamental similarity motivates our treatment of the passive as another instance of syntactic movement.
Our movement analysis of the passive is based on the premise that
theme arguments originate in the same structural position in both the
active and the passive. This means that the elementary trees for active
and passive participles both contain a complement position. However,
the relevant elementary trees differ in two important ways. First, in
the active, the agent argument is obligatorily linked
to
| (13) | a. | 
| b. | 
| |||
| Active verb: [+obj] | Passive verb: [-obj] | ||||||
Burzio 1986 was the first to note the correlation between the two above-mentioned properties and to state the generalization in (14).
| (14) | Burzio's generalization:
A verb form that does not express an agent argument in the specifier position cannot check objective case, and conversely. |
In what follows, we illustrate the derivation of a passive sentence like (15).
| (15) | The proposal was adopted. |
First, we substitute the theme argument the proposal in the elementary tree for the passive main verb in (13b). This yields (16a). We next substitute (16a) as the complement of the passive auxiliary verb be, as in (16b). In order to distinguish the auxiliary verb (be) from the main verb (adopted), we give it the syntactic category Aux, but we could just as easily treat it as another instance of V. We will treat auxiliary verbs, like raising verbs and passive participles, as lacking specifier positions. We then substitute the resulting structure as the complement of I, as in (16c).
| (16) | a. | 
| b. | 
| c. | 
| |||||
| Substitute theme argument in (14b) | Substitute (16a) as complement of passive auxiliary | Substitute (16b) as complement of I | |||||||||
Because of the inability of the passive participle to check objective case, the theme argument's case feature cannot be checked in the complement position. Since every case feature must be checked, the theme argument must move to the closest position in which case can be checked. This position is Spec(IP), where it is possible for the theme argument to check nominative case with finite I. The resulting final structure is shown in (17). (For simplicity, we omit the verb movement of the passive auxiliary be from V to I.)
| (17) | 
|
According to the analysis just presented, the passive is analogous to subject raising in the following way. In both cases, a noun phrase (the subject of the complement clause with subject raising, the object with passive) originates in a position where case can't be checked. This forces the relevant noun phrase (complement subject, object) to move to the closest position where case can be checked. Of course, subject raising and the passive aren't identical in every respect. There are two important differences between the two instances of movement. First, the path from the head of the chain to its tail contains a clause boundary (IP) in the case of subject raising, but not in the case of the passive.
|
| Recall that the term head has two completely different meanings that shouldn't be confused. The head of an X' structure is the syntactic category that immediately dominates a word or morpheme and projects an intermediate and a maximal projection. The head of a movement chain is the highest element in the chain. |
| (18) | a. | 
| b. | 
| |||
| Subject raising chain | Passive chain | ||||||
Second, the grammatical relation of the moved noun phrase doesn't
change in subject raising; it starts out as a subject and ends up as
one. In the passive, the grammatical relation of the moved noun phrase
does change - namely, from object to subject.
This section focuses on the passive of ECM verbs like
expect, which were introduced in connection
with head-spec licensing
in
The passive and nonfinite complementation
| (19) | a. | Your folks expect you to call. | |
| b. | You are expected to call. |
The elementary tree for expect in (19a) is given in (20a). In accordance with the previous discussion, the elementary tree for the passive participle expected is as in (20b). The difference between the two trees is analogous to that between the trees in (13); the only difference is the syntactic category of the complement (DP in the case of ordinary verbs, IP in the case of ECM verbs). Like (14b), (20b) is missing a specifier position; in accordance with Burzio's generalization, it also lacks the ability to check objective case.
| (20) | a. | 
| b. | 
| |||
| Active verb: [+obj] | Passive verb: [-obj] | ||||||
In what follows, we illustrate the derivation of (19b). The derivation of the complement clause is shown in (21); we assume that the complement subject moves from Spec(VP) to Spec(IP) to provide the complement clause with a subject (recall the subject requirement discussed in Chapter 3).
| (21) | a. | 
| b. | 
| c. | 
| |||||
| Structure of complement VP | Substitute (21a) as complement of nonfinite I | Move subject of complement clause | |||||||||
The subsequent steps of the derivation involving the matrix clause are as shown in (22).
| (22) | a. | 
| b. | 
| c. | 
| |||||
| Substitute (21c) as complement of passive participle of ECM verb | Substitute (22a) as complement of passive auxiliary | Substitute (22b) as complement of matrix I | |||||||||
In (22c), the subject of the complement clause cannot check case with the participle of the ECM verb in the head-spec configuration because the participle, being passive, lacks the ability to check case. Therefore, the complement subject must move to the nearest position where case can be checked. This is the matrix Spec(IP), where nominative case is checked. The resulting structure is shown in (23). (Once again, we omit V to I raising of the passive auxiliary for simplicity.)
| (23) | 
|
Consider now the chain headed by you in (23). The chain consists of three links, which occupy the matrix Spec(IP), the complement Spec(IP), and the complement Spec(VP). Chains whose links consist of these same three positions are also the result of subject raising, as we saw most recently in (18a). In this respect, then, the passive of ECM verbs is analogous to subject raising, as is evident from comparing the schematic structures in (24). The only difference is that the structure of ECM passives is slightly more complex because the matrix clause contains a passive auxiliary in addition to the main verb.
| (24) | a. | 
| b. |
| |||
| ECM passive chain | Subject raising chain | ||||||
The common source for the analogous chains in (18) and (24) is that ordinary passive verbs, subject raising verbs, and passive ECM verbs all lack a specifier position, as shown in (25), and therefore (by Burzio's Generalization) the ability to check case.
| (25) | b. |
| b. | 
| c. |
|
Although Burzio's generalization itself remains to be explained, it does allow us to understand the ungrammaticality of all three sentences in (26) as stemming from a single source. In all three sentences, the head (highlighted in italics), fails to be associated with an agent and hence fails to project Spec(VP),3 yet case would have to be checked on the underlined noun phrases contrary to Burzio's generalization, whether in the head-comp configuration, as in (26a), or in the head-spec configuration, as in (26b,c).
| (26) | a. | Ordinary passive: | * | { Itexpl, Thereexpl } was approved them. |
| b. | Raising: | * | { Itexpl, Thereexpl } seems | |
| c. | ECM passive: | * | { Itexpl, Thereexpl } is expected |
| The German examples in this section are given in the form of
subordinate clauses in order to abstract away from a syntactic
constraint on main clauses in the Germanic languages other than English
that is irrelevant for present purposes; this so-called V2 constraint is
discussed in Also, some of the German nouns have case endings, but for simplicity, we gloss case only on the determiners. |
| (27) | Active: | dass wir diesen Kandidaten unterstützt haben that we this.acc candidate supported have 'that we have supported this candidate' | ||
| (28) | a. | Passive: | dass dieser Kandidat unterstützt wurde that this.nom candidate supported became 'that this candidate was supported' | |
| b. | * | dass diesen Kandidaten unterstützt wurde that this.acc candidate supported became Intended meaning: 'that this candidate was supported' |
German also allows verbs to check the dative. Such verbs - for instance, helfen 'help' - continue to check the dative even in passive sentences, as shown in (29) and (30).4
| (29) | Active: | dass wir diesem Kandidaten geholfen haben that we this.dat candidate helped have 'that we helped this candidate' | ||
| (30) | a. | Passive: | * | dass dieser Kandidat geholfen wurde that this.nom candidate helped became Intended meaning: 'that this candidate was helped' |
| b. | ok | dass diesem Kandidaten geholfen wurde that this.dat candidate helped became 'that this candidate was helped' |
The accusative and the dative are both checked in the head-comp configuration by the verbs unterstützen 'support' and helfen 'help', respectively, but they differ in that the accusative alternates with the nominative, whereas the dative doesn't. What we mean by 'alternate' is simply that an accusative object in the active corresponds to a nominative subject in the passive, whereas a dative object in the active remains dative in the passive. The alternating cases (nominative, accusative) are known as structural cases (because which one occurs depends on the structural position of the argument bearing the case), whereas the nonalternating case (dative) is known as an inherent case.
The distinction between structural and inherent case has consequences for the formulation of Burzio's generalization. In view of the facts just presented, it holds only for verbs that check structural case.
| (31) | Burzio's generalization (revised formulation):
A verb form that does not express an agent argument in the specifier position cannot check structural case, and conversely. |
An important question that arises in connection with (30b) is what element checks the nominative case feature of the finite I. It is generally assumed that German has a silent expletive element, corresponding to English expletive it or there, that can check nominative case in Spec(IP). The structure of (30b) is then as in (32). (As usual, we omit the V to I movement of the passive auxiliary werden 'become'.)
| (32) | 
|
The silent expletive bears a number feature with the default value 'singular'. Evidence for this comes from the number agreement pattern in (33): the overt plural subject in (33a) agrees with a plural verb form, whereas the silent expletive in (33b) agrees with the corresponding singular verb form.
| (33) | a. | dass diese Kandidaten unterstützt | |
| b. | dass diesen Kandidaten geholfen |
Like German, Latin is a verb-final language with rich morphological case, and it patterns like German with regard to structural versus inherent case. As in German, the structural cases are nominative and accusative. The inherent cases include the remaining cases (apart from the vocative) - that is, the dative, genitive, and ablative. (34)-(37) illustrate the parallel with German, using the dative as a representative for the inherent cases.
| (34) | Active: | Avuncul-us puer- os adiuva-t. uncle nom.sg boy acc.pl help 3.sg.pres 'The uncle is helping the boys. | ||
| (35) | a. | Passive: | ok | Puer- i adiuva-nt- ur. boys nom.pl help 3.pl.pres passive 'The boys are being helped.' |
| b. | * | Puer- os adiuva-t- ur. boys acc.pl help 3.sg.pres passive Intended meaning: 'The boys are being helped.' | ||
| (36) | Active: | Avuncul-us puer- is subveni-t. uncle nom.sg boy dat.pl help 3.sg.pres 'The uncle is helping the boys. | ||
| (37) | a. | Passive: | * | Puer- i subveni-unt- ur. boys nom.pl help 3.pl.pres passive Intended meaning: 'The boys are being helped.' |
| b. | ok | Puer- is subveni-t- ur. boys dat.pl help 3.sg.pres passive 'The boys are being helped.' |
| (38) | Travis gave Betsy the receipts. | ||
| (39) | a. | Betsy was given the receipts. | |
| b. | * | The receipts were given Betsy. |
Not all languages show this pattern, however. German and Latin, for instance, have exactly the reverse pattern of that in (39); they allow the theme passive, but not the recipient passive. We will propose an explanation for this that relies on the distinction just introduced between structural and inherent case.
The grammaticality contrast for English in (39) can be derived straightforwardly as follows. The active and passive sentences have the schematic structures in (40) and (41), respectively. For clarity, (41) shows the structure before and after verb movement.
| (40) | a. | 
| ||||
| a. | 
| b. | 
|
In (41a), the higher VP shell lacks a specifier position for the agent, and therefore, by Burzio's generalization, the head is unable to check structural case. This property is preserved in the complex head that results from adjoining the lower verb to the higher one, as highlighted by the boxes. The recipient DP, which in the corresponding active sentence would check case with the complex verb in the head-spec configuration, must therefore move out of the VP shell structure. This yields (39a). In order to derive the ungrammatical (39b), the theme would have to move, rather than the recipient. But then the resulting chain would check case twice: the foot of the chain with the objective case feature on GET and the head of the chain with the nominative case feature on finite Infl. Meanwhile, the recipient DP would remain in its original location, unable to check case, exactly as before. As a result, the passive in (39b) is ungrammatical.
We turn now to the German counterparts of (40) and (41). In Chapter 8, we saw that German double object sentences surface with a dative-marked recipient and an accusative-marked theme. Given the distinction between structural and inherent case discussed earlier, the question arises of what happens in the passpive of double object sentences in German. As shown in (42) and (43), the argument with structural case can be promoted to subject, but the argument with inherent case cannot.
| (42) | dass ich dem Jungen den Roman gebe that I.nom the.dat boy the.acc novel give 'that I am giving the boy the novel' | ||
| (43) | a. | * | dass der Junge den Roman gegeben wird that the.nom boy the.acc novel given becomes Intended meaning: 'that the boy is being given the novel' |
| b. | ok | dass der Roman dem Jungen gegeben wird that the.nom novel the.dat boy given becomes 'that the novel is being given to the boy' |
The pattern in (43) is exactly the reverse of that in English. In other words, English allows the recipient passive, but not the theme passive, whereas German allows the theme passive, but not the recipient passive.
We propose to derive the German facts as follows. The structures for the active and the passive are shown in (44) and (45), respectively. As before, (45) shows the structure for the passive before and after verb movement.
| (44) | a. | 
| ||||
| a. | 
| b. | 
|
The passive morpheme on the higher V head in (45a) removes its ability to check structural case (though not its ability to check inherent case). As before, the properties of the higher head are preserved after verb movement. What the grammaticality of the theme passive suggests is that in German, the complex head's inability to check structural case is passed down to the adjoined lower verb. In other words, the passive morpheme affects the ability of the lower verb (via its trace) to check structural case in the head-comp configuration, as highlighted by the boxes in (45b). Since the theme argument cannot check structural case with its sister, it must move. Unlike in English, the recipient argument can check inherent case with the complex head, so the resulting (43b) is grammatical.
As expected given the similarity between German and Latin, Latin, too, allows only the theme passive, not the recipient passive.
| (46) | Active: | Avuncul-us puer- is libell- um mitt-it. uncle nom.sg boy dat.pl little.book acc.sg send 3.sg.pres 'The uncle is sending the boys a little book.' | ||
| (47) | a. | Passive | * | Puer- i libell-um mitt-unt- ur. boy nom.pl book acc.sg send 3.pl.pres passive Intended meaning: 'The boys are being sent a little book.' |
| b. | ok | Libell- us puer- is mitt-it- ur. little.book nom.sg boy dat.pl send 3.sg.pres passive 'The boys are being sent a little book.' |
1. By the criterion just mentioned, participial constructions as in (i) are true passive constructions, despite the absence of a passive auxiliary.
| (i) | a. | The shrubs planted (by our neighbors) are azaleas. | |
| b. | Planted in the shade (by an ignorant gardener), the cactus failed to thrive. |
Note the close parallel with the constructions in (ii), which contain a passive auxiliary.
| (ii) | a. | The shrubs that { were , got } planted (by our neighbors) are azaleas. | |
| b. | Having { been, gotten } planted in the shade (by an ignorant gardener), the cactus failed to thrive. |
2. Strictly speaking,
the verb-object combinations under discussion might better be referred
to as fixed expressions than as idioms. The so-called idiom chunk has a
very restricted distribution, but the interpretation of the entire
expressions is compositional, unlike in a true idiom.
3. We assume
that expletive it and there in (26) would substitute
directly into Spec(IP).
4. Certain archaic German
verbs govern the genitive, which patterns as an inherent case, as shown
in (i) and (ii), which are parallel to (29) and (30).
5. At least some
speakers of British English allow the theme passive in (39b), which was
possible in earlier stages of English. In American English, the theme
passive has been entirely replaced by the recipient passive, whereas
British English is not quite as far along in the replacement process.
| (i) | Active: | dass er der Ahnen gedachte that he the.gen ancestors commemorated 'that he commemorated the ancestors' | ||
| (ii) | a. | Passive: | * | dass die Ahnen gedacht wurden that the.nom ancestors commemorated became.pl Intended meaning: 'that the ancestors were commemorated' |
| b. | ok | dass der Ahnen gedacht wurde that the.gen ancestors commemorated became.sg 'that the ancestors were commemorated' |
| (1) | a. | The puppeteers might be arrested. | |
| b. | The puppeteers were arrested. |
B. In addition to be, English uses get as a passive auxiliary, as shown in (2).
| (2) | a. | The puppeteers might get arrested. | |
| b. | The puppeteers got arrested. |
There is a purely syntactic difference betweeen the two passive
auxiliaries. What is it?
Exercise 10.2
A. Using the xbar ch10 grammar tool, build
structures for the sentences in (1).
| (1) | a. | Standard English | The car needs to be washed. | |
| b. | Pittsburgh English | The car needs washed. |
B. Based on the evidence in (1), compare the syntactic properties
of Standard English versus Pittsburgh English need. Be explicit
but brief.
Exercise 10.3
A. Using the xbar ch10 grammar tool, build
structures for the sentences in (1) and (2).
| (1) | a. | We expect them to make headway. | |
| b. | We expect headway to be made. | ||
| c. | Headway is expected to be made. | ||
| (2) | a. | The media expect the guerillas to free the journalist. | |
| b. | The media expect the journalist to be freed by the guerillas. | ||
| c. | The journalist is expected to be freed by the guerillas. |
B. One of the sentences in (2) is structurally ambiguous. Which one
is it, and why?
Exercise 10.4
A. Using the xbar ch10 grammar tool, build
structures for the sentences in (1).
| (1) | a. | They proved there to be an error in the calculation. | |
| b. | There proved to be an error in the calculation. |
B. Which case is checked on the underlined noun phrases? How do you know?
C. In which licensing configuration(s) is case checked on the underlined noun phrases?
D. The syntactic properties of prove differ in (1a) and
(1b). Briefly explain how.
Exercise 10.5
Explain the pattern in (1). Do noun phrases (DPs) differ from clauses
(CPs, IPs) with respect to case-checking?
| (1) | a. | It was suspected that there was a problem with the O-ring. | |
| b. | That there was a problem with the O-ring was suspected. | ||
| c. | There was suspected to be a problem with the O-ring. | ||
| d. | * | There to be a problem with the O-ring was suspected. |
Consider the active sentence in (1) and its two theoretically possible passive counterparts in (2). Both sentences in (2) are intended to have the same meaning (namely, (2a)). However, as the contrast in (2) shows, it is grammatical to turn the subject of the complement clause in (1) into the matrix subject, but ungrammatical to do the same with the object of the complement clause. Briefly explain why this is so.
| (1) | They will expect her to hire him. | ||
| (2) | a. | ok | She will be expected to hire him. |
| b. | * | { He, Him } will be expected { she, her } to hire. |
Hint: See Exercise 9.2 C, D.
| (1) | They were determined to be U.S. citizens. | ||
| (2) | a. | ok | They were very determined to be U.S. citizens. |
| b. | ok | They were determined to be U.S. citizens by the INS. | |
| c. | * | They were very determined to be U.S. citizens by the INS. |
| (1) | a. | * | The path from I to V is intervened by an illicit node. |
| b. | * | In the next sentence, the original subject has been substituted by a pronoun. |
B. Omitting the by phrase in the sentences in (1) yields the grammaticality contrast in (2). Why?
| (2) | a. | * | The path from I to V is intervened. |
| b. | ok | In the next sentence, the original subject has been substituted. |