问题
选择题
When the boss came in, these workers pretended to________ carefully.
A．working
B．be working
C．work
D．have been working
答案
B
题目分析：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。
点评：pretend后面可以接不同的不定式：pretend to do假装要做…pretend to be doing假装正在做，pretend to have done假装已经做了什么，结合句意辨别。