英語文法解析 - 21 助動詞(Auxiliary verb)

助動詞就是用來幫助動詞的，所以請注意: 「一個句子裡面有助動詞就一定會有動詞」

 

助動詞功能如下：

1. 強調語氣

We do love chocolate.

2. 幫助動詞形成否定句

We do not love chocolate.

3. 幫助動詞形成疑問句

Do you love chocolate?

 

助動詞使用規則：

1. 助動詞後面必須用原形動詞

2. 不可連用兩個助動詞

If it will rain tomorrow, I will stay at home. 錯誤(同一個句子不可有兩個助動詞will)

If it rains tomorrow, I will stay at home. 正確

3. 用什麼問就用什麼回答

    Do you love chocolate?

    Yes, I do. / No, I don't.

4. 助動詞後面除ought外，一律不可接to

5. Want不可與would合用 (Do you want……? = Would you like….)

6. Cannot要合併(因為跟發音有關)

7. Could是敬語，求人勿用can you

8. Might比may的可能性小

9. Must (mustn’t)沒有過去式(=have to)，過去式要改用had to

10. 除了did和had to只用於過去式之外，其他像是could, would, might, should等字，並沒有時態上的限制，都可以用在現在式、過去式和未來式。

11. 要特別注意do, does, did，這三個字最容易被混淆，要注意用法: do用於現在式，does用在現在式第三人稱單數，did用在過去式。

 

助動詞種類：

表許可may, can, could (can的過去式), must not …

1. You may leave the office as soon as you have finished.

2. You can take three books home with you.

3. Last summer break we could stay up late on Sundays.

4. You must not leave your car unlocked.

表意願、想法do/does/did

1. Tom doesn't want to drink the milk.

 

表可能、推測may, might, could, can, must

1. She may/might know Tom’s address.

2. He may/might be waiting at the station when we arrive.

3. I guess he could be in the library.

4. Skiing on the hills can be quite dangerous.

5. There is a lot of noise form upstairs. It must be Tom.

6. It may rain this afternoon.

7. May I dance with you?

 

表能力Can (=am able to…), could (=was able to…)

1. I can’t (am not able to) pay you today.

2. Can you wait till tomorrow?

3. When he was young, he could (was able to) climb any tree in the forest.

4. Tom can do his homework by himself.

 

表建議、應該 should, ought to, had better

1. You should tell the police about it.

2. You ought to phone your parents. (只有ought後面才能接to)

3. I think you'd better ask Tom first. (or he will get offended.)

4. I should go home now. (should可當現代式使用)

 

必要must, have to

1. You must use a dictionary. I am tired of correcting your spelling errors.

2. Students must follow school rules.

 

表將來的事 will/would

1. Tom will take a break next week.

2. It won't rain tomorrow.

 

幫助動詞形成否定句或疑問句的句型:

1. He walks to school everyday.

(注意第三人稱單數動詞walk要加s，要改成疑問句或否定句就要用助動詞does)

(否定句) He doesn't walk to school everyday.

(要注意doesn't後面的walk要改回原形，助動詞後面只能接原形動詞)

(疑問句) Does he walk to school everyday? (注意walk變成原形了)

回答上面的疑問句要配合助動詞寫成Yes, he does. He walks to school everyday. 或No, he doesn't. He doesn't walk to school everyday. (not前面要加助動詞)

 

2. They watch TV every evening. (動詞watch是原形[表示現在式]，所以助動詞要用do)

(否定句) They don't watch TV every evening.

(疑問句) Do they watch TV every evening?

回答句：Yes, they do. They watch TV every evening. 或No, they don't. They don't watch TV every evening. (not前面要加助動詞)

 

3. They played basketball after school yesterday.

(動詞played是過去式，所以疑問句或否定句的助動詞要用did)

(否定句) They didn't play basketball after school yesterday.

(注意didn't後面的play要改成原形，助動詞後面只能接原形動詞)

(疑問句) Did they play basketball after school yesterday? (也要注意play變成原形了)

回答句要配合助動詞寫成Yes, they did. They played basketball after school yesterday. 或No, they didn't. They didn't play basketball after school yesterday.
(not前面要加助動詞)

 

那麼，疑問句到底什麼時候要用be動詞，什麼時候要用助動詞呢？

疑問句主詞後面若是形容詞，則句首要用be動詞(be動詞＋主詞＋形容詞?)，若主詞後面是動詞則句首要用助動詞(因為一個句子裡面有助動詞就會有動詞):

1. Are you hot? (這句主詞後面hot是形容詞，所以要用be動詞are)

2. Are you hungry? (這句主詞後面hungry是形容詞，所以要用be動詞are)

3. Do you walk to school?

(這句主詞後面walk是動詞，所以要用助動詞do表示現在式，若用did則表示過去式)

4. Do you speak English?

(這句主詞後面speak是動詞，所以要用助動詞do)

 

以上除了did和had to只用於過去式之外，其他的像是could, would, might, should等字，並沒有時態上的限制，都可以用在現在式、過去式和未來式。

 

Do, Does, Did的使用時機

Do, Does, Did這些字的使用時機很容易被混淆，要注意用法:

請牢記: Do用於現在式，Does用在第三人單數現在式，Did用在過去式。