Wh sentences

Who's on first ?
That's right !
Bud Abbott and Lou Costello

A different long-distance relationship is illustrated by the following sentences  :

1. Helen said the local member wanted to appoint an assistant
2. Helen said the local member wanted to appoint who ?
3. Who did Helen say the local member wanted to appoint ?

Either of sentences (2) and (3) might be spolen dy someone who didn't hear all of the first sentence. Note, however, that the who that replaced an assistant in (2) appears at the front of (3). This is evidence for a transformation that moves the wh- word to the front of the sentence, similar to the transformation that moves Aux to the front in other types of questions.

Sentence (2) is the deep structure. The fact that who is the direct object of the verb appoint is explicitly revealed in deep structure. In (3), despite the distance between who and appoint, it is understood that who is the direct object. This is accounted for by the transformation together with the fact that (2) is the deep structure that underlies (3).

As in the case of agreement, the distance can be indefinitely long  :

Who did Helen say the local member wanted the press secretary to try to convice the treasurer to get the committee to appoint ?

Unlike the agreement situation, the nature of the intervening structure makes a difference in dentence with wh- words such as who, when, what, and which, as shown in the following  :

Emily paid a visit to the local member who wants to appoint who ?
Who did Emily pay a visit to the local member who wants to appoint ?

Miss Marple asked Sherlock whether Poirot had solved the crime.
Who did Miss Marple ask whether Poirot had solved the crime ?

Who did Miss Marple ask Sherlock whether had solved the crime ?
What did Miss Marple ask Sherlock whether Poirot had solved ?

John Howard attacked the Herals's Canberra correspondent.
Who did John Howard attack ?
Whose Canberra correspondent did John Howard attack ?
Whose did John Howard attack Canberra correspondent ?

Alice talked to the white rabbit i the afternoon.
Who talked to the white rabbit in the afternoon.

Who did Alice talk to when ?
When did Alice talk to whom ?

Who when did Alice talk to ?
When to whom did Alice talk ?

The constrains on the formation of wh- question are rather complicated, though they are part of every Englis speaker's competence. If this were a book on English syntax, the rules and limitations would have be made explicit.