??虛擬語氣表示說話人的主觀愿望、猜疑、建議或與事實不符的假設等，而不表示客觀存在的事實。虛擬語氣是由句中的謂語動詞的特殊形式表現出來的。

??一、虛擬語氣謂語動詞的幾種表現形式

??1. 用在虛擬條件句中

??虛擬條件句及其主句的謂語形式可歸納如下:

??例1：I would certainly go if I had the time.

??例2：How nice it would be if you could stay a bit longer.

??例3：She would have come if we had invited her.

??注：如果條件從句中包含有were, had, should或could，有時可把if省略掉，但這時要把were, had, should或could放在主語前面(這種結構在口語中較少使用)。例如：

??1)Had we made (= If we had made ) adequate preparations, we might have succeeded.

??2)Were there no gravity, there would be no air around us.

??3)Should it rain tomorrow, the meeting would be put off.

??2. 用在含蓄條件句中

??句子中，假設的情況不用條件從句表示出來，而是用一個介詞短語來表示，句子的謂語形式也可遵循上表的規則。

??這種用法也常見于or, or else, otherwise和but后面的分句中。例如：

??1)Without music, the world would be a dull place.

??2)But for your help, we would have failed.

??3)She would have gone with us, but she didn’t have time.

??4)He must have had an accident, or he would have been here then.

??3.用在錯綜時間條件句中

??有時候，條件從句表示的動作和主句表示的動作發生的時間并不一致，這時，謂語動詞的形式要根據表示的時間來調整，這種句子可稱作錯綜時間條件句。例如：

??1)If you hadn’t watched television so late, you wouldn’t be so sleepy now.(此句為時間交錯的虛擬條件句，從句表示與過去事實相反的假設，主句則假設與現在情況相反)

??2)If you were in better health, we would have allowed you to join them in the work.(從句表示與現在事實相反的假設，主句則表示一種與過去事實相反的設想)

??4.用在wish后的賓語從句中

??這種句子主要表示愿望，that常省略。若指現在或將來的愿望，從句用過去時;若指過去沒有實現的愿望，從句用過去完成時。例如：

??1)I wish I had learned to play chess.(與過去事實相反)

??2)I wish I remembered his address.(與現在事實相反)

??3)I wish he would try again.(對將來情況的假設)

??若wish 后的賓語從句中用would，可以表示請求，通常意味著說話人的不快或不滿。例如：

??1)I wish you would help us.

??2)I wish you would stop asking such silly questions.