1. 介词后的动词用不定式还是动名词

　　动词用作介词宾语时，动词习惯上要用动名词。如：

　　According to the air traffic rules, you should switch off your mobile phone before boarding. 根据航空运输法规，登机前你应该关闭手机。

　　However hard you try, it is difficult to lose weight without cutting down the amount you eat. 不管你怎么努力去尝试，不减少你的进食而去瘦身都是很困难的。

　　但是，有两个词是例外，即表示“除……外”的介词 except和but 后通常接不定式作宾语，且这个不定式有时带to(若其前没有动词do)，有时不带 to(若其前有动词do)。如：

　　If he takes on this work, he will have no choice but to meet an even greater challenge. 如果他接受这个工作，他将别无选择，只能去迎接一个更大的挑战。

　　2. 关于介词后从句作宾语

　　用于介词后作宾语的从句，可以由what, who, which, when, where, how, why等，但通常不能是that 从句，遇此情况应在介词后加上 the fact。如：

　　Kelly loved her husband in spite of the fact that he drank too much. 尽管丈夫喝酒很凶，但凯莉还是爱着他。

　　Doris’ success lies in the fact that she is co-operative and eager to learn from others. 多丽丝的成功在于她的团结合作以及她积极向别人学习。

　　If it were not for the fact that she can’t sing, I would invite her to the party. 要不是因为她不会唱歌，我就会邀请她来参加晚会了。

　　3. 关于介词短语用作介词宾语

　　英语中有少数介词可接介词短语作宾语，这类介词常见的有from, until, except等。如：

　　I hope the rain holds off until after the picnic. 我希望野餐结束前不要下雨。

　　The window is never opened except in summer. 除夏天外，这扇窗户从未打开。

　　The next thing he saw was smoke rising from behind the house. 随后，他看见的是，烟正从屋子后面升起。

　　4. to do还是to doing

　　to有时是不定式符号，有时是介词，所以英语有时用to do，有时用to doing。对于许多同学来说，to do容易理解，但 to doing 则很容易搞错。从中学英语所接触的知识来看，to doing的用法主要仅于某些固定搭配，如：

　　adapt to doing sth 适应做某事

　　admit to doing sth 承认做了某事

　　apply to doing sth适用于做某事

　　object to doing sth 反对做某事

　　see to doing sth 负责做某事

　　stick to doing sth 坚持做某事

　　take to doing sth 喜欢上做某事

　　apply oneself to doing sth 专心于做某事

　　devote…to doing sth把……献给做某事

　　be opposed to doing sth 反对做某事

　　reduce sb to doing sth 使某人沦为做某事

　　key to doing sth 做某事的关键

　　limit to doing sth 做某事的限度

　　pay attention to doing sth 注意做某事

　　set one’s mind to doing sth 决心做某事

　　be used to doing sth 习惯于做某事

　　get down to doing sth开始做某事

　　look forward to doing sth 盼望做某事

　　in addition to doing sth 除做某事之外

　　The key to solving the problem is to meet the demand made by the customers. 解决这个问题的关键就是满足顾客的要求。

　　Be sure to pay attention to protecting the environment and be considerate while traveling. 外出旅游时务必注意保护环境，为他人着想。

　　We are looking forward to taking part in the opening ceremony of the art to be held next week. 我们盼望能参加下星期举行的艺术节开幕式。