英語(yǔ)if的用法歸納
IF是一個(gè)英語(yǔ)單詞，名詞、連詞，作名詞時(shí)意思是“條件，設(shè)想；不確定的情況”，作連詞時(shí)意思是“（表?xiàng)l件）如果；（表假設(shè)）要是，假如；無(wú)論何時(shí)；雖然，即使；（用于間接疑問(wèn)）是否；（用于禮貌問(wèn)詢）是否；當(dāng)，每次；（與情態(tài)動(dòng)詞連用）表婉轉(zhuǎn)客氣；這不是……，要是……多好；或許不；就算；盡管”。以下是小編為大家?guī)?lái)的英語(yǔ)if的用法歸納，希望能幫助到大家。
英語(yǔ)if的用法歸納 篇1
if從句和虛擬語(yǔ)氣:
1. 當(dāng)if后面接一般現(xiàn)在時(shí)的動(dòng)詞時(shí),表示對(duì)將來(lái)的一種推測(cè). if sb do sth sb will/shall do sth. If you go with me,you shall be rewarded.
2. 當(dāng)if后面接一般過(guò)去時(shí)的動(dòng)詞時(shí),則是一種虛擬語(yǔ)氣. if sb did sth sb would/should do sth. If I didn't make that mistake,I would't have suffered such a failure.
3. 當(dāng)if后面接什么時(shí)態(tài)都可以時(shí)，if為“是否”的意思，句子為賓語(yǔ)從句. sb do sth if sb do sth. He said if rain was stop. 由if引導(dǎo)的條件狀語(yǔ)從句，時(shí)態(tài)應(yīng)該是主將從現(xiàn)，就是說(shuō)主句用一般將來(lái)時(shí)，而從句用一般現(xiàn)在時(shí)表示將來(lái)。
例如 If it doesn't rain tomorrow,I will visit my former school. 這里從句就用一般現(xiàn)在時(shí)。當(dāng)然if引導(dǎo)的從句也可以用虛擬語(yǔ)氣，例如 If I got up early in the morning,I wouldn't miss the train.
If 引導(dǎo)的條件狀語(yǔ)從句大盤點(diǎn)
一. 條件狀語(yǔ)從句表示主句動(dòng)作發(fā)生的條件.引導(dǎo)條件狀語(yǔ)從句的連詞不多,初中階段最常用的引導(dǎo)詞為If(如果).切記：引導(dǎo)條件狀語(yǔ)從句的If,不能用whether來(lái)替換.例句：
(1)Please call me if he is at home.(假如他在家,請(qǐng)給我打電話.)
(2)You must see a doctor if you are ill.(如果你生病了,就必須去看醫(yī)生.)
(3)Don’t go to the beach if it rains.(倘若下雨就不要去海灘了.)
(4)If it rains tomorrow,I won’t go there with you.(如果明天下雨的.話,我就不和你一起去那兒了.)
二.條件狀語(yǔ)從句的時(shí)態(tài)：
1.主句用一般將來(lái)時(shí),條件狀語(yǔ)從句用一般現(xiàn)在時(shí)表將來(lái).如：例句(4)
2.當(dāng)主句含情態(tài)動(dòng)詞時(shí),條件狀語(yǔ)從句用一般現(xiàn)在時(shí).如：例句(2)
3.當(dāng)主句為祈使句,條件狀語(yǔ)從句用一般現(xiàn)在時(shí).如：例句(1)和 (3)
三.正確區(qū)分If 引導(dǎo)的條件狀語(yǔ)從句和If 引導(dǎo)的賓語(yǔ)從句
在賓語(yǔ)從句中If為“是否”,如表示“將來(lái)”時(shí),則用將來(lái)時(shí)態(tài),賓語(yǔ)從句一般位于主句之后;而在條件狀語(yǔ)從句中If的意思為“如果”,主句用一般將來(lái)時(shí),從句用一般現(xiàn)在時(shí)表將來(lái),且從句位置比較靈活,可位于主句之后也可位于主句之前.請(qǐng)比較：
If you keep on working hard at English,you can learn it well.
如果你繼續(xù)努力學(xué)習(xí)英語(yǔ),你就能夠?qū)W好它.(條件狀語(yǔ)從句)
My little brother wants to know if my father take him to the zoo on Sunday.
我的小弟弟想知道星期天我父親是否將帶他去動(dòng)物園.(賓語(yǔ)從句)
四.If 引導(dǎo)條件狀語(yǔ)從句與祈使句的轉(zhuǎn)換：
主語(yǔ)為you的條件狀語(yǔ)從句還可與“祈使句 + and / or + 簡(jiǎn)單句” 句式
互換.例如：If you work harder,you’ll pass the exam.= Work harder,and you’ll pass the exam.
If you don’t hurry up,you’ll miss the train.= Hurry up,or you’ll miss the train.
英語(yǔ)if的用法歸納 篇2
if的用法有：
1、(表示條件)如果，主句用將來(lái)時(shí)，if從句用現(xiàn)在時(shí)表示將來(lái)
He will come if you invite him.
如果你請(qǐng)他，他會(huì)來(lái)的。
2、(表示虛擬)假如，要是
時(shí)態(tài)：可以表示過(guò)去，現(xiàn)在和將來(lái)的情況.它的基本特點(diǎn)是時(shí)態(tài)退后。
a、同現(xiàn)在事實(shí)相反的假設(shè)。
句型 ：條件從句 主句
一般過(guò)去時(shí) should( would) +動(dòng)詞原形
If they were here,they would help you.
b、表示于過(guò)去事實(shí)相反的假設(shè)。
句型：條件從句 主句
過(guò)去完成時(shí) should(would) have+ 過(guò)去分詞
If she had worked harder,she would have succeeded.
The rice would not have been burnt if you had been more careful.
If my lawyer had been here last Saturday,he would have prevented me from going.
If he had come yesterday,I should / would have told him about it.
含義：He did not come yesterday,so I did not tell him about it.
If he had not been ill and missed many classes,he would have made greater progress.
含義：He was ill and missed many lessons,so he did not make greater progress.
c、表示對(duì)將來(lái)的假想
句型：條件從句 主句
一般過(guò)去時(shí) should+ 動(dòng)詞原形
were+ 不定式 would + 動(dòng)詞原形
should+ 動(dòng)詞原形
If you succeeded,everything would be all right.
If you should succeed,everything would be all right.
If you were to succeed,everything would be all right.
3、是否 = whether 連接賓語(yǔ)從句
I wonder if she is ill.
不知她是否病了。
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