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(一)情態動詞

1、情態動詞在句中沒有人稱和數的變化。

7．　 在It is time that, I would rather that句式中從句謂語動詞用過去式。例如：

It is time we went to bed.

I would rather he came next week.

第二節 實戰演練

6．　 在有些句型中如：It is important (necessary、natural、strange等) + that從句中的謂語動詞用should + 動詞原形，should可以省略。例如：

It is necessary that the doctor (should) be sent there at once.

5．　 在有些動詞如：suggest、insist、order等動詞后，從句謂語動詞用“should + 動詞原形”，should可以省略。例如：

He suggested that we (should) discuss the problem right now.

4．　 動詞wish后的賓語從句中，謂語動詞可用過去式、過去完成式或would、might加原形。

例如：I wish I were as strong as you.

He wished I would stay with us.

She wished I had attended the meeting yesterday.

3．　 表示與將來事實相反的謂語形式。

例如：If they came tomorrow, we would told them about it. (In fact, they won’t come tomorrow。)

2．　 表示與過去事實相反的謂語形式。

例如：If I had left a little earlier, I would have caught the early bus. (In fact, I didn’t catch the bus.)

虛擬語氣表示說話人的意愿、假設、猜測或建議。虛擬語氣不表示客觀存在的事實，謂語動詞用特殊的形式表示虛擬語氣。

1．　 表示與現在事實相反時的謂語形式。

例如：If Tom were hungry, he would eat the bread. (In fact, Tom isn’t hungry.)

4. must與have to比較

must側重于個人意志和主觀上的必要，have to側重于客觀上的必要。如果用于過去時態或將來時態時，則要用have to的相應時態來代替must。但must可用于間接引語中表示過去的必要或義務。

My brother was very ill，so I had to call for the doctor in the middle of the night.

我弟弟病得很厲害，我只得半夜里把醫生請來。(一般過去時)

I haven't got any money with me，so I'll have to borrow some from my friend.

我身上沒有錢，只好向朋友借點了。(一般將來時)

He said that they must work hard.他說他們必須努力工作。

3. have to的疑問句

句型：Do(Does, Did, Will)+主語+have to +動詞原形？

Do you have to study maths now？

你現在必須學數字嗎？

Yes，I do.是的，必須學。

No，I don't(have to)。不，不必學。

Did he have to ask the question？

他非要問那個問題嗎？

Yes，he did.是的。

No，he didn't(have to).不。