5. 在有些动词如:suggest、insist、order等动词后,从句谓语动词用“should + 动词原形”,should可以省略。例如:
He suggested that we (should) discuss the problem right now.
4. 动词wish后的宾语从句中,谓语动词可用过去式、过去完成式或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. 表示与将来事实相反的谓语形式。
从句 |
主句 |
动词过去式 should + 动词原形 were to + 动词原形 |
would (should、could) + 动词原形 |
例如:If they came tomorrow, we would told them about it. (In fact, they won’t come tomorrow。)
2. 表示与过去事实相反的谓语形式。
从句 |
主句 |
had + 过去分词 |
would
(should、could) + have +过去分词 |
例如:If I had left a little earlier, I would have caught the early bus. (In fact, I didn’t catch the bus.)
虚拟语气表示说话人的意愿、假设、猜测或建议。虚拟语气不表示客观存在的事实,谓语动词用特殊的形式表示虚拟语气。
1. 表示与现在事实相反时的谓语形式。
从句 |
主句 |
过去式 (be和were) |
would
(should、could)+ 动词原形 |
例如:If Tom were hungry, he would eat the bread. (In fact, Tom isn’t hungry.)
4. must与have to比较
must侧重于个人意志和主观上的必要,have to侧重于客观上的必要。如果用于过去时态或将来时态时,则要用have to的相应时态来代替must。但must可用于间接引语中表示过去的必要或义务。
My brother was very ill,so I had to call for the doctor in the middle of the night.
我弟弟病得很厉害,我只得半夜里把医生请来。(一般过去时)
I haven't got any money with me,so I'll have to borrow some from my friend.
我身上没有钱,只好向朋友借点了。(一般将来时)
He said that they must work hard.他说他们必须努力工作。
3. have to的疑问句
句型:Do(Does, Did, Will)+主语+have to +动词原形?
Do you have to study maths now?
你现在必须学数字吗?
Yes,I do.是的,必须学。
No,I don't(have to)。不,不必学。
Did he have to ask the question?
他非要问那个问题吗?
Yes,he did.是的。
No,he didn't(have to).不。
2. have to的否定句
句型:主语+don't(doesn't, didn’t, will not)have to+动词原形
You don't have to walk so fast.
你不必走那么快。
He will not have to buy a new coat next year.
明年,他没必要买新外衣了。
1. have(has)to +动词原形
have(has)to后面要用动词原形。当主语为第三人称单数时用has to,当句子是过去时用had to。
We have to leave now.
我们不得不现在就离开。
He has to work on Sunday.
他不得不在周日工作。
I had to do my homework last Sunday.
上周日,我不得不做作业。
2.表示推测的用法
can , could ,may ,might ,must 皆可用来表示推测,其用法如下:
a.could ,might 表示推测时不表示时态,其推测的程度不如can ,may。
b.can ,could 用于否定句和疑问句中。
句型:主语+ can't , couldn't +be +动词ing.(否定句)
Can ,Could +主语 +be +动词 ing.(疑问句)
They can't be cleaning the room now.他们现在不可能在打扫房间。
c.may ,might , must 用在肯定句中。
句型:主语+ may ,might ,must +be +动词 -ing
(表示对现在发生动作的推测)
He must be sleeping . 他现在肯定在睡觉。
d.但如果上述这些词 (must ,can't… ) + have +过去分词则指对过去已发生的事进行推测。
The road is wet. It must have rained last night .
地是湿的;昨天晚上肯定下雨了。
There isn't any water on the road . It (can't ) couldn't have rained last night .
地面上一个水滴都没有,昨天不可能下雨了。
(四) have to的用法
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