试题详情

The _____ is very hard, I can’t answer it.

_______ the math problem is difficult, I’ll try very hard to work it out.

It is very hard to _____ him to give up smoking and drinking alcohol.

The ______ to build up space stations on the Mars is, if we cannot say it is impossible, at least ve

etimes it is very difficult to _______ some of the English words. Even the native speaker can not he