if的用法與單詞資料
if的基本釋義為如果、即使、是否。那么你對(duì)if的使用方法了解多少呢?以下是由學(xué)習(xí)啦小編整理關(guān)于if的用法的內(nèi)容，希望大家喜歡!
if的用法
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
1)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.
if的單詞資料
發(fā)音
英 [ɪf] 美 [ɪf]
釋義
conj. (表?xiàng)l件)如果;即使;是否;(表假設(shè))假如
1. (表示條件)如果
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
If I were you, I would never do that.
如果我是你,我決不做那件事。
3. (表示讓步)即使
We'll go even if it rains.
即使下雨我們也要去。
4. 是否
I wonder if she is ill.
不知她是否病了。
5. (表示因果關(guān)系)每一次...的時(shí)候(總是會(huì))
If I feel any doubt, I inquire.
我一感到有疑問(wèn)就隨時(shí)詢問(wèn)。
n. 條件;設(shè)想
There are too many ifs in his offer.
他的提議中條件太多了。
縮寫(xiě)
IF=i.f.
if.
縮寫(xiě)詞 abbr.
1. =information feedback 信息回饋
2. =interferon
3. =intermediate frequency 中頻
i.f.
縮寫(xiě)詞 abbr.
=intermediate frequency 中頻
if的擴(kuò)展知識(shí)
1. if和whether在賓語(yǔ)從句中，都表“是否”，可換用，if更口語(yǔ)化，whether正式些。
當(dāng)有or not時(shí)， 一般用whether，而不用if。
He wants to know if/whether you can help him.
She wonders whether you'll go or not.
2. if可引起條件狀語(yǔ)從句，whether不用于狀語(yǔ)從句。
If you work hard, you'll succeed.
If I were you , I would do it in another way.
3. whether可引起主語(yǔ)從句，表語(yǔ)從句，if不能用于這兩種情況。
Whether you can finish it in time or not depends on yourself.
The question is whether they'll help you.
4. if在名詞性從句中只能引導(dǎo)動(dòng)詞后的賓語(yǔ)，whether可通用。
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