含有下面三個表達(dá)方式的句子體現(xiàn)虛擬語氣的形式是固定的：

　　lest(以免，防備), for fear that(惟恐), on condition that(在..條件下)

　　它們后面句子的謂語動詞的形式都是：(should)+ 動詞原形。

　　7 it is time 是...的時候了。

　　這個結(jié)構(gòu)有以下兩種變形形式，所用虛擬語氣形式都一樣：it is high time / it is about time.

　　這三個結(jié)構(gòu)后面加的句子謂語動詞都用一般過去時來體現(xiàn)虛擬語氣。

　　8 注意以下兩種情況下should + 動詞原形中should不能省略。

　　這里should表示一種語氣，經(jīng)常被翻譯成“竟然”。

　　a. 四個動詞：think, believe, expect, suspect.

　　它們的否定或者疑問形式后面加句子，句子謂語動詞用：should + 動詞原形，should不能省略。

　　I don't believe that he should be cheated. 我不相信他也會被騙。

　　b. it is a pity, it is a shame 真遺憾，it is strange 真怪

　　以上三個結(jié)構(gòu)后面加的句子謂語動詞用：should + 動詞原形，should不能省略。

　　錯綜時態(tài)的虛擬語氣

　　錯綜時態(tài)的虛擬語氣即指主句和從句在表達(dá)是與什么時態(tài)的事實相反上并不一致(比如主句要表達(dá)與現(xiàn)在事實相反而從句要表達(dá)與過去事實相反)，這種情況要采用“對號入座”的方法來處理，即主從句結(jié)構(gòu)分別采用與其表達(dá)時態(tài)對應(yīng)的結(jié)構(gòu)。

　　60. If I hadn’t stood under the ladder to catch you when you fell, you _A_ now.

　　A wouldn't be smiling B couldn't have smiled C won't smile D didn't smile

　　2. If you had studied the problem carefully yesterday, _C_.

　　A you won’t find any difficulty now B you would not have found any difficulty now

　　C you would not find any difficulty now D you have not found any difficulty now

　　3. He would be studying at the university now if he _C_ the entrance examination.

　　A passed B have passed C had passed D should have passed

　　16. It is a shame that he _B_ that poor little girl!

　　A deceived B should deceive C deceive D deceiving

　　18. Mrs. bliss kept the door and the windows shut lest the noise outside _D_ her son's sleep. [lest(以免，防備) 后面句子的謂語動詞的形式都是：(should)+ 動詞原形]

　　A would interfere with B had interfered with

　　C interfered with D should interfere with