阅读下面的文章，注意介词结构的使用功能和含义：
The oldest stone buildings in the world are pyramids. They have stood for nearly 5,000 years, and it seems likely that they will continue to stand for thousands of years yet. There are over eighty of them scattered along the banks of the Nile, some of which are different in shape from the true pyramids. The most famous of these are the Step pyramids and the Bent pyramids.
Some of the pyramids still look much the same as they must have done when they were built thousands of years ago. Most of the damage suffered by the others has been at the hands of men who were looking for treasure or, more often, for stone to use in modern buildings. The dry climate of Egypt has helped to preserve the pyramids, and their very shape has made them less likely to fall into ，变成为)ruin.
英语文化介绍与外国人交流的时候，什么问题不能问?
你结婚了吗?/Are you married or single?不要问
你怎么还没有结婚呢?/How come/why youre still single? 不要问
你离婚了， 什么原因呢?两人合不来吗?/Youre divorced. What was the reason? Couldnt you two get along? 不要问
你信教吗?/Do you go to church? 不要问
你信什么教?/Whats your religion? 不要问
情态动词
英语中常用的情态动词有can, may, must, ought, need, might, could。在一定的场合下,shall, should, will, would也可用作情态动词。情态动词都有词义，并需要同另一个动词的原形构成谓语。除ought后跟不定式以外，其他情态动词通常都跟动词原形构成谓语，有时也跟动词的完成或进行式构成谓语， 如： They must have gone to bed. He must be working in the lab. 情态动词的否定式都是由情态动词+ not + 构成。如：can not, need not, should not。