英語四級語法虛擬語氣詳解

　　英語四級語法虛擬語氣詳解：主要以下幾點 1. if 引導(dǎo)的虛擬語氣 2. 倒裝形式 3.固定句型：It is (was)+形容詞(或過去分詞)+that…… 4、名詞性從句中要用過去時或should+動詞原型構(gòu)成虛擬語氣。 5、would rather, had rather后的從句動詞用相當(dāng)于陳述語氣的過去時來表示現(xiàn)在或?qū)戆l(fā)生的動作

　　1. if 引導(dǎo)的虛擬語氣

　　a. 指現(xiàn)在的事： 前面用were/過去式，后面用 should (would) +動詞原形

　　例句 If he were here, he would help you now.

　　b. 指過去的事： 前面用過去完成時，后面用 should (would) have+ 過去分詞

　　例句 If she had worked harder, she would have succeeded.

　　If he had come yesterday, I should / would have told him about it.

　　If he had not been ill and missed many classes, he would have made greater progress.

　　c. 指將來的事： 前面用were/過去式，后面用 should+ 動詞原形

　　或前面用 were+ 不定式，后面用 would + 動詞原形

　　或前面用 should+ 動詞原形，后面用 would + 動詞原形

　　例句 If you succeeded, everything would be all right.

　　If you were to succeed, everything would be all right.

　　If you should succeed, everything would be all right.

　　2. 倒裝形式

　　Were I you (=if I were you) , I would get up early in the morning.

　　Had you arrived at the station ten minutes earlier yesterday(=If you had arrived…), you could have caught the train.

　　Should it rain (=If it should rain), the crops would be saved.

　　3、固定句型

　　“It is (was)+形容詞(或過去分詞)+that……”結(jié)構(gòu)中的虛擬語氣

　　It is necessary that we (should 可省略,下同)have a walk now.

　　It was necessary that we (should) make everything ready ahead of time.

　　4、名詞性從句中要用過去時或should+動詞原型構(gòu)成虛擬語氣。如：It is time we went home.

　　5、would rather,had rather后的從句動詞用相當(dāng)于陳述語氣的過去時來表示現(xiàn)在或?qū)戆l(fā)生的動作。

　　如：I would rather you went with her.我寧愿你跟她走。

　　只有當(dāng)would rather后面動作的主體與前面主語一致時才可以用不帶 to的動詞不定式，

　　如：I’d rather take the important letter with me.