My father was preparing for his speech __   my mother was doing some washing last night.

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

My father was preparing for his speech __ my mother was doing some washing last night.

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

My father was preparing for his speech __ my mother was doing some washing last night.

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

My father was preparing for his speech _________ my mother was doing some washing last night．

1. A.
   if
2. B.
   while
3. C.
   unless
4. D.
   until