(2) a. Difficult though the problem is, ...
     b. Difficult though the students believe the problem is, ...

(3) a. * Difficult though I wonder why the problem is, (I don't know for sure.)
     b. * Difficult though Lukas enjoys problems which are, (he can't always solve them.)

A. Here are the structures for the sentences in (2):

B. Here are the structures for the sentences in (3):

C. The examples in (2) obey the island constraints while those in (3) do not. The contrast shows that though preposing is another construction involving wh- type movement, even though the moved element is a predicate rather than an argument or adjunct. Both of the sentences in (3) violate subjacency and (3b) violates the ECP as well, according to the definition of the ECP given in the text. Because the predicate is extracted from a relative clause, neither the antecedent government clause nor the lexical government clause (defined in terms of the recursive notion of lexical government domain) is satisfied.