-When did your computer go wrong?

    -Last night, while I_______ some music from a website.

A. downloaded                                  B. am downloading  

C. was downloading                                      D. have downloaded

 When did your brother __________ the army?

A.join                  B. join in              C. take part in

--- When did your father come back last night?

--- He didn’t come back _______ he finished all the work.                                                           

A. until                                  B. while                              C. if                           D. unless

When did your father_____ your mother?

— Could you please tell me 　　　　?

— In three days.

A. when will your course start

B. when your course will start

C. when your course started

D. when did your course start