You should be polite to your teachers.

　　你应该对你的老师有礼貌。

　　(2)表示推测。意为"想必一定；照说应该"。

　　They should be there by now，I think.

　　我想他们可能在那儿了。

　　(3)表示惊异。意为"竟然"。

　　It's surprising that Tom should cheat in the exam.

　　汤姆竟然在考试中作弊，真是不可思议。

　　6．will(would)

　　(1)表示意愿。用于各种人称的陈述句中。

　　①I will do anything for you.

　　我愿为你做任何事。

　　②They would not let him in because he was poorly dressed.

　　他们不让他进去，因为他衣着破旧。

　　(2)表示请求。用于疑问句中。would语气更委婉。

　　①Will you please take a message for him?

　　你能给他带个口信吗？

　　②Would you mind cleaning the window?

　　请你把窗户擦一下，好吗？

　　(3)表示某种倾向或习惯，would表示过去的习惯。

　　①The boy will sit there hour after hour looking at people going by.

　　那个男孩常常坐在那里好几个钟头，看着人们走过。

　　②Every time she was in trouble，she would go to him for help.

　　每次遇到麻烦，她都会向他求助。

　　[名师点津]　

　　would和used to的区别

　　(1)would表示过去习惯性的动作，不涉及现在的情况。

　　Each time his mother's birthday came，he would buy her a present.

每次到他母亲生日的时候，他都要给她买一件礼物。