问题补充:
The math problem seems very easy, but in fact it is very difficult.
A. to work out
B. being worked out
C. working out
D. to be worked out.
答案:
(答案→)A. to work out
B. being worked out
C. working out
D. to be worked out.
解析:考查非谓语动词。句型S(人,物)+ be + adj. + to do,句子的主语在逻辑关系上为不定式动作的宾语,to do中的动词是及物动词时,不用被动,不及物动词后要接介词。句意:这道数学题看起来非常容易,但事实上却很难解出来。故A正确。