1） be +现在分词，构成进行时态，例如： They are having a meeting. 他们正在开会。 English is becoming more and more important. 英语现在越来越重要。 2) be + 过去分词，构成被动语态，例如： The window was broken by Tom.. 窗户是汤姆打碎的。 English is taught throughout the world. 世界各地都教英语。 3） be + 动词不定式，可表示下列内容： a. 表示最近、未来的计划或安排，例如： He is to go to New York next week.. 他下周要去纽约。 We are to teach the freshpersons. 我们要教新生。 说明： 这种用法也可以说成是一种将来时态表达法。 b. 表示命令，例如： You are to explain this. 对此你要做出解释。 He is to come to the office this afternoon. 要他今天下午来办公室。 c. 征求意见，例如： 补充： 1 I am a girl. 2 She is lazy . 3 Her telephone number is 333-589. 4 He is to explain this . 5 I am sleeping . 6 He is at home .很抱歉，我只知道这几种，希望能帮助你。
Be quiet, please! I am a good student. You are an excellent teacher. He is very kind. He was a policeman. They were married. He has been in Canada for one year. I am being in trouble.本回答被提问者采纳