Some people fear that ________ airpollution may bring about changes in _______ weather around the world.

你的同学到你家玩，你想把他或她介绍给你的母亲认识，你应该对你母亲说 ____________。

They were _____about this____ football match.

Did you telephone Uncle Sam our plan for the Christmas holidays on his farm? — Yes, he was happy about our arrival, and he eagerly asked when ______

________— No, he is sick.