英语中的be动词可以作为“系动词、助动词”使用，在短语和句型中也十分常见，表“是、成为”之意。be动词随主语的人称、数以及时态的变化而变化。
be动词形式有：am/is/are/was/were/being/been
一、be动词作为助动词
be动词作为助动词，可用于不同时态和语态之中，它随主语的人称、数以及时态的变化而变化。be动词在不同时态中的形式如下：
(1) 一般现在时：am/is/are
She is our Chinese teacher. 她是我们的语文老师。
They are from Chengdu China. 他们来自中国成都。
(2) 一般过去时：was/were
Their parents were already in sixties. 他们的父母已经60多岁了。
(3) 一般将来时：will/shall be
We will be late for the class. 我们上课会迟到的。
(4) 现在进行时：am/is/are v-ing
They are watching TV in the living room now. 他们正在客厅看电视。
(5) 过去进行时：was/were v-ing
He was doing his homework when I called him yesterday night. 昨晚我给他打电话时，他正在写作业。
(6) 将来进行时：will/shall be v-ing
I will be playing the piano between 8 PM and 8:30 PM tomorrow night. 明天上午8点至8点半，我会弹钢琴。
(7) 现在完成时：have/has been
I have been to Shanghai with my parents before. 我和父母以前去过上海。
(8) 过去完成时：had been
I had been in this company since it was created in 2010. 自从这家公司2010年创立以来我就一直在这里工作。
