你會正確使用虛擬語氣的倒裝形式嗎

請看典型考題：

__________ your address，I would have written to you.

A. Did I know                                        B. Were I to know

C. Had I known                                      D. If I should know

此題應選 C。這是虛擬語氣的倒裝形式。當虛擬條件句中含有 were，had，should，could等動詞時，可以將if省略，然后將 were，had，should，could 等詞移至句首：

1. If he should fail，he would kill himself.

→Should he fail，he would kill himself.

萬一失敗，他就會自殺。

2. If I were you，I would do it at once.

→Were I you，I would do it at once.

假若我是你，我就會馬上做。

3. If I could do it，I would.

→Could I do it，I would.

要是我能做此事，我一定會做。

4. If he had seen you yesterday，he would haveasked you about it.

→Had he seen you yesterday，he would haveasked you about it.

他昨天要是看到了你，他就會問你這事了。

順便說一句，以上移至句首的 had不一定是助動詞，如果是實義動詞也可倒裝：

If he had money，he would buy a car.

→Had he money，he would buy a car.

他要是有錢，他就會買一輛小車。