36 People have discovered a new source of energy.
D. A new source of energy has discovered
A. A new source of energy have been discovered.
B. A new source of energy have been discovered by people.
C. A new source of energy has been discovered.

37 I last wrote to them two years ago.
A. I have not written to them for two years.
C. The last time I wrote to them was two years ago.
B. It is two years ago since I wrote to them.
D. The last time I wrote to them was two years .
 
38
It usually takes her ______.
B. two hours to do her homework
D. two hours done her homework
A. two hours doing homework
C. homework two hours to do

39 The doctor advised Robert ______ to lose weight.
B. to take more exercise if he wanted
D. that he should take more exercise in order that
C. that he takes more exercise
A. to take more exercise so that he could

40 She went to bed as soon as she turned off the lights.
B. No sooner had she turned off the lights when she went to bed.
C. No sooner had she turned off the lights that she went to bed.
D. No sooner had she turned off the lights than she had gone to bed.
A. No sooner had she turned off the lights than she went to bed.