可以引起與事實相反的方式狀語從句，用虛擬語氣

由as if、as though引起的與事實相反的句子，不論主句的謂語是現在時或者說過去時，其謂語表示的時間概念和句子結構，都基本上與wish后的賓語從句相同。例：

John pretends as if he didn’t know the thing at all, but in fact he knows it very well.

(用過去式表示與現在事實相反的假設)

The old man looked at the picture, he felt as though he had gone back to time 20 years ago.

(用過去完成式表示與過去相反的事實)

They talked and talked as if they would never meet again (would+動詞原形，表示與將來事實相反)