助動詞(auxiliary verb)本身沒有詞義，不可單獨作句子謂語。它僅僅是用來幫助主要動詞構成各種時態、語態、語氣以及否定和疑問結構。
在講解助動詞的主要功能之前，大家先觀察下面兩組句子。
語境展示
Ⅰ. a. We are working in the rice field.
b. He didn’t go home last night.
c. They do like the film that they have seen many times.
Ⅱ. a. I have (got) to remind you of writing to her.
b. You’d better tell her the whole story.
c. If it’s all the same to you, I’d rather work at home.
總結歸納
一
助動詞的主要功能
1. 助動詞可以和其他主要動詞一起構成時態和語態。常用的助動詞有be (am, is, are, was, were, been, being), do (does, did), have (has, had, having)。
2. 助動詞可以用來加強語氣，表示強調。
3. 助動詞可以用來構成否定句或疑問句。
二
短語助動詞
短語助動詞由一個助動詞和另外一個或兩個詞構成，其功能相當於一個助動詞。常見的如：have (got) to, had better, would rather … (than), be to, be likely to, be supposed to, ought to, used to, be about to, be able to。
1. have to的意思接近must，但must強調說話人的意願，而have to表示客觀上的必要性，常可譯為“不得不”，其否定形式not have to表示“不必；不需要”。例如：
You must take good care of her.
You have to have a visa to go to another country.
2. would rather … (than) 表示“寧願，寧可”，其意思相當於prefer to。例如：
I would rather wear clothes made of natural fibers.
= I prefer to wear clothes made of natural fibers.
3. be to可表示：
“打算做某事或計劃好要做的事”(意思接近於be going to)，例如：
The president is to make a statement tomorrow.
“該做某事”(意思接近於should, must, ought to, have to等)，例如：
You are not to smoke in the room.
“能做某事” (意思接近於can, may)，例如：
How am I to pay such a debt?
“將來必然發生的事”，例如：
They said goodbye, not knowing they were never to meet again.
4. be likely to表示“某事有可能發生或可能是真的”。例如：
Once people have seen that something actually works, they are much more likely to accept change.
5. be supposed to表示“理應，被認為”。例如：
You’re not supposed to play football in the classroom.
6. used to與would均可表示習慣，例如：
When we were children we used to / would go skating every winter.
但是，二者之間的不同在於used to有現在已無此習慣的含義，並可表一次性動作。例如：
I used to have a car like this. (此處不能用would)
即學即練
Ⅰ. 請在空白處填入適當的助動詞(每空一詞)。
1. We go to see you first when we arrive there.
2. She lived there for ten years, so she didn’t want to leave.
3. What you do if you had a billion?
4. she always carry an umbrella?
5. I think he likely to win.
Ⅱ. 請翻譯下列句子(注意助動詞的使用)。
1. 你打電話時，我正在洗澡。
2. 孩子們被照顧得很好。
3. 我已經學了三年法語。
4. 我不知道那部小說的名字。
5. 我確實認為你應該去。
答案角
Ⅰ. 1. will / shall
2. had
3. would
4. Does
5. is
Ⅱ. 1. I was having a bath when you called.
2. The children were taken good care of.
3. I have learned French for three years.
4. I don’t know the name of the novel.
5. I do think you should go.
