介詞的作用：
1. 表示地點：after, along, at, below, by, of, near, over, through, under 等.如：
　　Near the village the boys are skating on the ice. 男孩子們正在村子附近的冰上滑冰.
　　They lay down under the shade of a tree. 他們躺在一棵樹的樹陰下.
2. 表示時間：about, after, across, at, during, for, in, of, till, until 等.如：
　　After class he will tell us about the accident. 課后他將告訴我們有關(guān)事故的情況.
　　A heavy rain has been falling across three days. 一場大雨下了整整三天.
　　The accident happened during the night. 事故發(fā)生在夜間.
3. 表示動作：at, across, around, on, over, under 等.如：
　　The earth goes around the sun. 地球繞太陽運行.
　　The car is under repair. 汽車在修理中.
4. 表示比較：as, like, above, over, with 等.如：
　　She was something like her sister. 她有幾份像她的妹妹.
　　Chinese is much more difficult in contrast with English. 和英語相比,漢語難得多.
5. 表示原因：about, for, from, with 等.如：
　　Don't worry about my lessons. 不要擔(dān)心我的功課.
　　Business kept me from coming. 我因事不能來.
　　He was angry with what I did. 他對我所做的很氣憤.
6. 表示條件：to, with, without 等.如：
　　Without your advice, he would have failed. 沒有你的忠告他可能已經(jīng)失敗了.
7. 表示手段、方式：as, by, in, with 等.如：
　　He behaved as a drunkard. 他的舉止如同醉漢一樣.
　　Learn the new words by heart. 記住這些生詞.
　　We see with our eyes. 我們用眼睛看.
8. 表示距離、數(shù)量：from, in, within 等.如：
　　My house is ten miles from the school. 我家離學(xué)校十英里.
　　They were thirty in all. 他們總共有三十人.
9. 表示目的：as, for 等.如：
　　I only said it as a joke. 我只是把它當(dāng)作笑話講的.
　　It's time for class. 到上課的時間了.
10. 表示讓步：for, with 等.如：
　　For all his effort, he didn't succeed. 雖然他做了一番努力,仍不能成功.
　　With all his money, he is unhappy. 盡管他有錢,但他并不快樂.
　　for 還可以引導(dǎo)插入語,例如：
　　I, for one, shall vote against the proposal. 我也投票反對這個提議