助动词和实义动词一起构成谓语，帮助实义动词构成各种时态、语态及构成否定或疑问等结构。常用的助动词有be，do，does，did，have，has，had，will，shall，would，should等。

助动词be

助动词be主要有am，is，are，was，were五种形式，与现在分词构成进行时态。

I am reading a story book. 我正在看故事书。

Sarah is drawing a picture. 莎拉正在画画。

Tom was looking out of the window. 汤姆那时在往窗外看。

助动词do

助动词do主要有do，does，did三种形式。

与动词原形连用构成疑问句或否定句，还可以构成简略回答。

What do you like ? 你喜欢什么？

Does she like music? 她喜欢音乐吗？

Yes，she does . 是的，她喜欢。

助动词have

助动词have主要有have，has两种形式，与过去分词构成现在完成时。

Have you been to Disneyland? 你去过迪士尼乐园吗？

Jim has been to China twice. 吉姆去过中国两次。

I haven't done my homework. 我还没做完作业。

助动词will/would, shall/should

助动词will，shall用于构成一般将来时，would，should用于构成过去将来时；shall，should主要用第一人称，will，would可用于一切人称。

We will meet at the bus station. 我们将在车站见。

Perhaps I shall pay a visit to England this summer. 或许今年夏天我将去英格兰旅行。

　特别提示

1．will，would，shall，should除了表示将来时间以外，更多的是作情态动词。

2．shall，should用于第一人称表示将来时，在口语中常被will，would替代。

一、用正确的be动词填空。

1．—What's the weather like?

—It _______(is, are) cloudy.

2．—Look at the boys. __________(Are, Is) they your brothers?

—Yes, they are.

3．—The crayons __________(are, aren't) on the table.

　They are under the table.

4．—__________(Is, Are) it a cat?

—No, it isn't.

5．—__________(Are, Is) your mother a doctor?

—Yes, she is.

二、从括号里选择正确的动词形式填空。

1．He __________ have classes in the morning.( don't/doesn't)

2．Lily and Lucy __________ good friends.(is/are)

3．__________ you finished your paper?(Has/Have)

4．He __________ have classes in the morning.( don't/doesn't)

5．__________ she watch TV every day?(Does/Do)

三、按要求完成下列句子。

1．We went to the U.S. last month.（变成一般疑问句）

2．Does he like apple juice?（作肯定回答）

3．She made a poster last night.（变成否定句）

4．Do you have a dog?（作否定回答）

5．They bought some key rings for us in Mexico.（对画线部分提问）

一、1．is

2．Are

3．aren't

4．Is

5．Is

二、1．doesn't

2．are

3．Have

4．doesn't

5．Does

三、1．Did you go to the U.S. last month?

2．Yes, he does.

3．She didn't make a poster last night.

4．No, I don't.

5．What did they buy for us in Mexico?