在大學(xué)英語四級考試中，單獨考察英語四級語法的題幾乎沒有，但是英語四級語法知識點卻貫穿整張試卷，下面是英語四級頻道為大家整理的大學(xué)英語四級語法知識，希望可以為大家?guī)韼椭A(yù)祝大家考試順利過關(guān)。
2019年12月大學(xué)英語四級語法大全目錄
虛擬條件句的倒裝
虛擬條件句的從句部分如果含有were, should, 或had, 可將if省略，再把were, should或had 移到從句句首，實行倒裝。
Were they here now, they could help us.
=If they were here now, they could help us.
Had you come earlier, you would have met him
=If you had come earlier, you would have met him.
Should it rain, the crops would be saved.
=Were it to rain, the crops would be saved.
注意：
在虛擬語氣的從句中，動詞'be'的過去時態(tài)一律用"were"，不用was， 即在從句中be用were代替。
If I were you, I would go to look for him.
如果我是你，就會去找他。
If he were here, everything would be all right.
如果他在這兒，一切都會好的。
典型例題
_____ to do the work, I should do it some other day.
A. If were I B. I were C. Were I D. Was I
答案C. 在虛擬條件狀語中如果有were, should, had這三個詞，通常將if省略，主語提前, 變成 were, should, had +主語的形式。但要注意，在虛擬條件狀語從句中，省略連詞的倒裝形式的句首不能用動詞的縮略形式。如我們可說 Were I not to do., 而不能說 Weren't I to do.