[Grammar] Wh questions and prepositions

[pinguino03]

Hello,

I am having a hard time explaining to my students when they should keep a preposition at the end of a question. For example:

Mike is from Boston.
Where is Mike from?

George is in the kitchen.
Where is George? (Definitely not Where is George in?-but why?)

Other examples:

John arrived at noon.
When did John arrive? (no preposition)

Alice waited for Sally.
Whom did Alice wait for? (here we keep the preposition. Why?)

Thanks so much!

Jill

 

[5jj]

On its own, where? means in/at/to which place? These prepositions are there not necessary before the word. Other prepositions are.