问题
选择题
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
题目分析：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。