5. 在有些動(dòng)詞如:suggest、insist、order等動(dòng)詞后,從句謂語動(dòng)詞用“should + 動(dòng)詞原形”,should可以省略。例如:
He suggested that we (should) discuss the problem right now.
4. 動(dòng)詞wish后的賓語從句中,謂語動(dòng)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(shí)相反的謂語形式。
從句 |
主句 |
動(dòng)詞過去式 should + 動(dòng)詞原形 were to + 動(dòng)詞原形 |
would (should、could) + 動(dòng)詞原形 |
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(shí)相反的謂語形式。
從句 |
主句 |
had + 過去分詞 |
would
(should、could) + have +過去分詞 |
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(shè)、猜測或建議。虛擬語氣不表示客觀存在的事實(shí),謂語動(dòng)詞用特殊的形式表示虛擬語氣。
1. 表示與現(xiàn)在事實(shí)相反時(shí)的謂語形式。
從句 |
主句 |
過去式 (be和were) |
would
(should、could)+ 動(dòng)詞原形 |
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(cè)重于個(gè)人意志和主觀上的必要,have to側(cè)重于客觀上的必要。如果用于過去時(shí)態(tài)或?qū)頃r(shí)態(tài)時(shí),則要用have to的相應(yīng)時(shí)態(tài)來代替must。但must可用于間接引語中表示過去的必要或義務(wù)。
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(yī)生請來。(一般過去時(shí))
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(diǎn)了。(一般將來時(shí))
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(dòng)詞原形?
Do you have to study maths now?
你現(xiàn)在必須學(xué)數(shù)字嗎?
Yes,I do.是的,必須學(xué)。
No,I don't(have to)。不,不必學(xué)。
Did he have to ask the question?
他非要問那個(gè)問題嗎?
Yes,he did.是的。
No,he didn't(have to).不。
2. have to的否定句
句型:主語+don't(doesn't, didn’t, will not)have to+動(dòng)詞原形
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,他沒必要買新外衣了。
1. have(has)to +動(dòng)詞原形
have(has)to后面要用動(dòng)詞原形。當(dāng)主語為第三人稱單數(shù)時(shí)用has to,當(dāng)句子是過去時(shí)用had to。
We have to leave now.
我們不得不現(xiàn)在就離開。
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,我不得不做作業(yè)。
2.表示推測的用法
can , could ,may ,might ,must 皆可用來表示推測,其用法如下:
a.could ,might 表示推測時(shí)不表示時(shí)態(tài),其推測的程度不如can ,may。
b.can ,could 用于否定句和疑問句中。
句型:主語+ can't , couldn't +be +動(dòng)詞ing.(否定句)
Can ,Could +主語 +be +動(dòng)詞 ing.(疑問句)
They can't be cleaning the room now.他們現(xiàn)在不可能在打掃房間。
c.may ,might , must 用在肯定句中。
句型:主語+ may ,might ,must +be +動(dòng)詞 -ing
(表示對現(xiàn)在發(fā)生動(dòng)作的推測)
He must be sleeping . 他現(xiàn)在肯定在睡覺。
d.但如果上述這些詞 (must ,can't… ) + have +過去分詞則指對過去已發(fā)生的事進(jìn)行推測。
The road is wet. It must have rained last night .
地是濕的;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 .
地面上一個(gè)水滴都沒有,昨天不可能下雨了。
(四) have to的用法
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