Yesterday one of my classes was practicing wh- questions in past simple (Stretch Starter, Oxford University Press, p 93). The activity involves creating a question for the given answer. The first is provided as an example, and I've filled in the rest:
1A: Where did you go? B: I went to a movie.
2A: (Who did she come with?) B: She came with James.
3A: (How long did they stay [for]?) B: They stayed for a week.
4A: (Where did Jack go [to]? B: Jack went to Allan's house.
5A: (When did you call [me] [*at]?) B: I called you at 9:00.
For 2, about half the students wrote *'Who did she come?', which is ungrammatical, but I couldn't think why, either on the spot yesterday, or now, 24 hours later. In 3 and 4, the preposition is optional (and unnatural for me). In 5, the preposition is ungrammatical.
Huddleston and Pullum (A Student's Guide to English Grammar, p 137-9) don't discuss it, and I can't find it anywhere else. Has anyone got any thoughts about this?