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if的使用方法了解多少呢?以下是由學習啦小編整理關于if的用法的內容，希望大家喜歡!
if的用法
1.(表示條件)如果 ,主句用將來時,if從句用現在時表示將來
He will come if you invite him.
如果你請他,他會來的.
2.(表示虛擬)假如,要是
1)時態：可以表示過去,現在和將來的情況.它的基本特點是時態退后.
a.同現在事實相反的假設.
句型 ：條件從句 主句
一般過去時 should( would) +動詞原形
If they were here,they would help you.
b.表示于過去事實相反的假設.
句型：條件從句 主句
過去完成時 should(would) have+ 過去分詞
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.表示對將來的假想
句型：條件從句 主句
一般過去時 should+ 動詞原形
were+ 不定式 would + 動詞原形
should+ 動詞原形
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 連接賓語從句
I wonder if she is ill.
不知她是否病了.
if的單詞資料
發音
英 [ɪf] 美 [ɪf]
釋義
conj. (表條件)如果;即使;是否;(表假設)假如
1. (表示條件)如果
He will come if you invite him.
如果你請他,他會來的。
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. (表示因果關系)每一次...的時候(總是會)
If I feel any doubt, I inquire.
我一感到有疑問就隨時詢問。
n. 條件;設想
There are too many ifs in his offer.
他的提議中條件太多了。
縮寫
IF=i.f.
if.
縮寫詞 abbr.
1. =information feedback 信息回饋
2. =interferon
3. =intermediate frequency 中頻
i.f.
縮寫詞 abbr.
=intermediate frequency 中頻
if的擴展知識
1. if和whether在賓語從句中，都表“是否”，可換用，if更口語化，whether正式些。
當有or not時， 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可引起條件狀語從句，whether不用于狀語從句。
If you work hard, you'll succeed.
If I were you , I would do it in another way.
3. whether可引起主語從句，表語從句，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動詞后的賓語，whether可通用。
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