if的用法总结
if的用法总结英语？
if的用法总结英语？
if作为连词，引导条件状语从句，表示“假如”、“如果”等意思。在复合句中如果主句用将来时，则if引导的状语从句用一般现在时。
if可以引导让步状语从句，表示“即使是”、“虽说”之意。
if作为连词可以引导宾语从句，和whether意思相同。
if的用法有：
(表示条件)如果，主句用将来时，if从句用现在时表示将来；
(表示虚拟)假如，要是；
是否 ，等于whether
连接宾语从句。
if的用法，请解释？
一、if作为连词还可以引导宾语从句，意为是否。引导宾语从句时和whether意思相同。例如：Lilyaskedif／whethershelikedit. 莉莉问她是否喜欢它。
二、if还可以引导让步状语从句。这时if当作“即使是”，“虽说”解。例如：Ifshe’spoor，atleastshe’shonest． 虽说她很穷，但至少她还是诚实的。
三、if引导时间状语从句，当if做“当”或“无论何时”解而不含有条件之义时，if从句中的时态与主句中的时态相同。例如：Ifyoumixyellowandblue，yougetgreen．你将黄色与蓝色混合，便会得到绿色。
四、if与其它一些介词的连用。as与if连用，它的意思是：“仿佛、好像”同样引导从句。例如：Itisn’tasifwearerich．(Wearenotrich．)我们不像富有的样子。(即我们不富有)五、asif还可以引导感叹句。例如：AsifIwouldallowit!好像我会答应似的！
英语If用法？
1.(表示条件)如果 ,主句用将来时,if从句用现在时表示将来 He will come if you invite him. 如果你请他,他会来的.
2.(表示虚拟)假如,要是
1）时态：可以表示过去,现在和将来的情况.它的基本特点是时态退后.
a.同现在事实相反的假设. 句型 ：条件从句 主句 一般过去时 should( would) 动词原形 If they were here,they would help you.
b.表示于过去事实相反的假设.
句型：条件从句 主句 过去完成时 should(would) have 过去分词 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.
含义：
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.
含义：
He was ill and missed many lessons,so he did not make greater progress.
c.表示对将来的假想
句型：
条件从句 主句 一般过去时 should 动词原形 were 不定式 would 动词原形 should 动词原形
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 连接宾语从句 I wonder if she is ill. 不知她是否病了.