2021屆高三英語重點詞匯與短語-
有時條件從句中的動作和主句中的動作發生的時間不一致，這時動詞的形式要根據它所表示的時間加以調整。
if you had listened to the doctor,you would be all right now.如果你當初聽了醫生的話，身體現在就好了。(從句動作指過去，主句動作指現在)
if you had practised speaking english more, you would be able to speak it fluently.
如果你多練習講英語，現在就能講得很流利了。
①省略連詞if
在書面語中，如果虛擬條件從句中有were，had或should，可以把if省略，而把這幾個 詞放到主語之前，構成主謂倒裝。如：
should he come(if he should come), tell him to ring me up.
他要是來了，讓他給我打個電話。
were i you(if i were you),i would not do it.我要是你，就不做這事。
had he been more careful(if he had been more careful), such mistakes could have been avoided.如果他細心些，這些錯誤本來是可以避免的。
在虛擬條件句中，省略連詞的倒裝形式，其句首不能用助動詞的縮略否定式。如我們可以說：
were it not for the expense, i would go to paris. 但不能說： weren’t it for the expense,i would go to paris.
②用介詞短語代替條件狀語從句
有時假設的情況并不用條件從句表示出來，而是通過介詞短語來表示。
如：
without air(if there were no air), there would be no living things.
如果沒有空氣的話，就不會有生物了。
but for your help(if it hadn’t been for your help)i couldn?t have done it.
要是沒有你的幫助，我就不可能完成這件事。
假設的情況有時可以通過上下文或其他方式表現出來。如：
i was busy that day. otherwise i would have gone there with them. (if i hadn’t been busy that day, i would have gone there with them. )我那天很忙，否則，我就和他們一起去那兒了。(如果我那天不忙的話，我就……)
i would have finished the work, but i have been ill.(if i hadn’t been ill, i would have finished the work.)我本來該完成這項工作的，但我生病了。（如果我沒生病的話，我就會完成……）
（5）省去條件從句或主句
表示虛擬敢的主名或從句有時可以省略，但其含義仍可以推知。
①省去條件從句
you could have washed your clothes yourself.你本可以自己洗衣服的。（省去了“if you had wanted to”）（事實是：你自己沒洗衣服，因為你不想洗。）
②省去主句（常用以表示愿望）
if my grandmother were with me!如果我的祖母與我在一起多好啊！（事實是：祖母已不在世。）
if only she had not left!如果她沒走就好了!（事實是：她已經走了。）
if only the wind would stop!風要是停了該多好!（事實是：風停的可能性很小。）
【考點透視 考例精析】
[考例1] i couldn’t do my homework with all that noise ______.
a.going on b.goes on c.went on d.to go on