be动词，即am，is，αre，wαs，were，意思为"是"，是连接主语和表语的动词，有时不译。如，

I am a teacher.我是一个老师！

She is old.她年纪大了！

We are happy.我们很高兴！

He was at home.他在家。

They were right.他们是对的！

be动词有时跟其他动词结合，形成各种时态和语态，叫助动词！这时be动词不单独翻译，没有单独的词义！如下列句子：

I am going to see a movie this evening.我打算今晚看电影。

We are thinking of it.我们正在考虑！

He was sleeping in the bed.他正躺在床上！

They have been there twice.他们已去那两次了！

The watch is made in Sweden.这表瑞士产的。

除be可作助动词，do，does，did，will，sha1l，have，hαs，hαd也作助动词，形成各种时态。

do和does是一般现在时的助动词。形成否定句和疑问句，肯定句不需要,这时，do和does无词义，不译！

Do they live inBeijing?

Does Bob love his family?

We don't take art classes.

What do they have for dinner?

did是一般过去时的助动词，形成否定句和疑问句，肯定句不需要,这时，did无词义，不译！

Dⅰd you stay at home？ 丫es，I did.

She didn't meet us.

will,shall是一般将来时态的助动词，有词义，表"将要"，"会"，如，Ⅰ will ride to work.

have.has 是现在完成时的助动词，与其后的过去分词结合成谓语，表示"已经...."不单独翻译！

I have seen this film.

He has gone home.

had是过去完成时的助动词，与其后的过去分词结合成谓语，表示"已经...."也不单独翻译！

I had left there before he arrived.

上述be动词及其他助动词的用法，需要仔细捉摸，结合句子理解才能掌握！

欢迎交流和讨论！