Ms Qian, this problem is __________ difficult for me!— Don’t complain __________ , Henry. You should use your head.

－He buys __________ books, but he doesn’t read them at all.

The two words have the same pronunciation, but they are different ______ spelling and meaning

下列各句中，没有语病的一句是（ ）

In aerospace devices the weight of thenecessary power producing equipment is _____