When the boss came in these workers pretended to carefully.A. workingB. be working C. wor

问题补充：

When the boss came in, these workers pretended to carefully.

A. working

B. be working

C. work

D. have been working

答案：

A. working

(答案→)B. be working

C. work

D. have been working

解析：考查pretend的用法：pretend to be doing假装正在做，句意是：当老板进来时，他假装在认真工作。选B。