Extends discussion of ambiguity with adverbs in infinitival constructions to a similar ambiguity involving relative clauses, where a single linear order can be assigned two distinct hierarchical structures that support distinct interpretations. Another adverbial ambiguity involves verb phrases where the verb is modified by two adverbs, one to the left and one to the right of the verb – a single linear order with two distinct hierarchical structures. Displacing an adverb to the front of a clause eliminates the potential ambiguity. This constraint on displacement applies also to direct yes/no-questions where the displaced auxiliary can only be interpreted as modifying the main clause verb. The syntax of direct yes/no-questions requires an auxiliary do when the corresponding indicative contains only a finite main verb. This auxiliary occurs also in tag questions, verb phrase ellipsis, and wh-interrogatives, with an interrogative pronoun at the front of the clause. A syntactic analysis of yes/no- and wh-questions discusses wh-displacement in other constructions (clefts, pseudo-clefts, and headless relatives).