英语的be动词有三个is am are 用法:助词 1.(与动词的现在分词连用,构成各种进行时态)正在...,在...I won't be free this afternoon.I'll be seeing a friend off.我今天下午没空,我要给朋友送行.What were you doing from 9 to 11 this morning?今天上午九点到十一点你在做什么?He is working.他在工作.2.(与及物动词的过去分词连用,构成被动语态)被...The problem was solved long ago.问题早解决了.It will be discussed tomorrow.此事将在明天讨论.3.【旧】(与不及物动词go,come,rise等的过去分词连用,构成完成时)已经...The sun is set.太阳已经下山.4.(与动词不定式连用,表示职责、义务、意图、约定、可能性等)应该做...,必须做 ...;预定做...;会做...The President is to visit Japan next week.总统将于下周访问日本.You're to do your homework before you watch TV.你应该做了功课再看电视.不及物动词 vi.1.是[L] At that time he was the chair of the department.当时他是系主任.I am a teacher and they are my students.我是老师,他们是我的学生.She is very young.她非常年轻.2.(表示时间、度、量、价值等)是;值;等于[L] The watch is 100 dollars.这表值一百元.3.(常用祈使语气或不定式)要,得;成为;变成[L] Be quiet,please.请安静.4.(与there连用)有[L] There are a lot of tourists there.那里有许多观光客.5.逗留,(继续)呆[L] He will be here all next week.下周他将一直呆在这儿.6.在[Q] Tony is in the office.托尼在办公室里.7.存在 Whatever is has every reason for being.存在的东西总有其存在的理由.8.听任 If she's sleeping,let her be.如果她在睡觉,就别惊动她.