Question

【題目】I didn’t know his telephone number. ________ it, I ________ then.

A. Had I known; would ring him up B. Should I know; would have rung him up

C. If I knew; would ring him up D. Had I known; would have rung him up

Answer 1

【答案】D

【解析】考查虛擬語氣。由“I didn’t know his telephone number.”可知，是對過去的假設。If 從句用had done，主句用would/could/might have done。而if從句中省略了if，把had提到句首，故選D。

【名師解析】虛擬語氣在if引導的條件句中的用法：

一、1. 表示與現(xiàn)在事實相反的虛擬條件句

If+主語+動詞的過去式（be用were）, 主語+would(should/could/might)+動詞原形

1)If I were you, I should study English.

2)I would certainly go if I had time.

2. 表示與過去事實相反的虛擬條件句

If+主語+had done, 主語+would（should/could/might）+have done

1)If you had taken my advice, you would not have failed in the test.

3.表示與將來事實相反的虛擬條件句

If+主語+should（were to）+動詞原形/動詞的過去式, 主語+would（could/should/might）+動詞原形

1)If it were to rain tomorrow, the meeting would be put off.

二、 錯綜時間虛擬條件句 即條件從句與主句所指時間不一致，如從句指過去，而主句即指的是現(xiàn)在或?qū)�來，此時應根據(jù)具體的語境情況，結(jié)合上面提到的三種基本類型對時態(tài)作相應的調(diào)整。

1）If it had rained last night, the ground would be wet now.

要是昨晚下過雨的話，現(xiàn)在地面就會是濕的

一般來說虛擬語氣中的混合時態(tài)的句子都有具體的時間詞來進行提示的，比如說

2）You would be much better now if you had taken my advice. 假若你當時聽我的話，你現(xiàn)在就會好多了。（從句與過去事實相反，主句與現(xiàn)在事實相反。）

3）If we had arrived at the shopping mall earlier, we would get more gifts now. 如果我們早點來商場的話（過去的時間虛擬），我們現(xiàn)在就可以拿更多的禮物了（現(xiàn)在的虛擬）。 這是兩個不同時間的虛擬語氣，有相應的時間詞來提示的，now來提示后句的時間是現(xiàn)在而不是和前面一樣的過去。

4）If you had worked hard，you would get higher marks. 如果沒有明確的時間狀語，可以根據(jù)語境而定。如這個句子，很明顯是在說過去要是認真點，現(xiàn)在就不會分數(shù)低。從句與過去事實相反，謂語用had done；主句與現(xiàn)在事實相反謂語用would do。

三、if省略句。在條件句中可省略if, 把were, had, should提到句首，變?yōu)榈寡b句式。如：

1)If I were you, I would study harder. → Were I you, I would study harder.

2)If you had come earlier, you would catch the bus. → Had you come earlier, you would catch the bus.

3)If it should rain tomorrow, we would not go climbing→ Should it rain tomorrow, we would not go climbing.

注意：若省略的條件句中的謂語動詞是否定形式時，不能用動詞的縮略形式。

如：我們可以說：Were it not for the expense, I would go abroad now.

但不能說：Weren't it for the expense, I would go abroad now.