1. Why must you keep complaining __________?

A. all the time      B. at times  

C. at a time      D. at one time

2. __________ I am is concerned, the idea is wholly crazy.

A. As long as     B. As far as  

C. As soon as     D. As well as

3. It was not until mid-night __________ he went back home after the experiment.

A. when      B. /        

C. that      D. before