Old version (Fall 2006) - current version here

Yes-no and wh- questions

Questions can be divided into yes-no questions (also known as polar questions) and wh- questions (also known as constituent questions), according to the expected answer. As the name implies, the answer to a yes-no question is either 'yes' or 'no.' The answer to a wh- question is expressed by a constituent that corresponds to the wh- phrase in the question. Wh- phrases are so called because they generally begin with wh- in English (who, what, which, where, when, why). How counts as a wh- expression by virtue of its meaning, even though it doesn't begin with wh-. The term wh- phrase is standardly used even for languages other than English.

The distinction betwen yes-no questions and wh- questions is illustrated in (1) and (2).

(1)   Yes-no question   Has he called? { Yes, no. }
(2) a. Wh- question   Who just came in? The boy from next door.
b. Who(m) did you invite? All my friends.
c. When did she call? After dinner.
d. Why did he do that? Out of ignorance.
e. How did you fix it? With the right tool.

Direct and indirect questions

Another distinction that can be drawn is between direct questions and indirect questions. Direct questions are main clauses, whereas indirect questions are part of a larger matrix sentence. Direct questions are generally used to elicit information. They are associated with characteristic intonation contours, which are represented in standard orthography by a question mark. Indirect question are generally used to report about direct questions and are not associated with a special intonation.

The questions in (1) and (2) are all direct questions. The indirect questions corresponding to them are given in (3) and (4). Here and in what follows, indirect questions are enclosed in square brackets.

(3)   Indirect yes-no question   I can't remember [ { whether, if } he has called.
(4) a. Indirect wh- question   I can't remember [ who just came in. ]
b. I can't remember [ who(m) you invited. ]
c. I can't remember [ when she called. ]
d. I can't remember [ why he did that. ]
e. I can't remember [ how you fixed it. ]

(5) gives examples of various syntactic contexts in which indirect questions occur.

(5) a. Complement of adjective   I'm not sure [ whether they are coming. ]
b. Complement of preposition The question of [ whether they are coming ] remains unresolved.
c. Complement of verb She asked [ whether they are coming. ]
d. Subject [ Whether they are coming ] remains up in the air.

Finally, indirect questions can be finite or nonfinite, as shown in (6) and (7). Notice that if, in contrast to whether, requires finite complements.

(6) a. Indirect yes-no question, finite   They can't remember [ { whether, if } they should turn off the lights. ]
b. nonfinite   They can't remember [ whether to turn off the lights. ]
(7) a. Indirect wh- question, finite   They can't remember [ what they should pay attention to. ]
b. nonfinite   They can't remember [ what to pay attention to. ]