问题补充:
He is often made for twelve hours a day by his boss.
A. work
B. working
C. to work
D. to be working
答案:
A. work
B. working
(答案→)C. to work
D. to be working
解析:在主动结构中make 后加省去to 的动词不定式做宾语补足语。但当make 用于被动结构中时,主动结构中省去的to还得加上。即be made to do sth。句意:他经常被老板迫使一天工作12个小时。故选C。