Paul jumped to his feet and pretended ____very hard when his boss came.

A. to work　　 　 B. to be working

C. working　　 D. to have worked

Paul jumped to his feet and pretended ________ very hard when his boss came．

1. A.
   to work
2. B.
   to be working
3. C.
   working
4. D.
   to have worked