一、基本用法
以as if (as though)引導(dǎo)的方式狀語從句或表語從句，有時(shí)用虛擬語氣，若表示與現(xiàn)在事實(shí)相反，謂語動(dòng)詞用一般過去時(shí);若表示與過去事實(shí)相反，用過去完成時(shí);表示將來的可能性不大，用would (might, could)+動(dòng)詞原形：
He acts as if he knew me. 他顯得認(rèn)識我似的。
They treat me as though I were a stranger. 他們待我如陌生人。
He talks as if he had been abroad. 他說起話來好像曾經(jīng)出過國。
二、兩點(diǎn)說明
(1) 從句所表示的內(nèi)容若為事實(shí)或可能為事實(shí)，也可用陳述語氣：
It looks as if we’ll be late. 我們似乎要遲到了。
This meat tastes as if it has already gone bad. 這肉吃起來似乎已經(jīng)壞了。
在現(xiàn)代英語中，有時(shí)即使從句內(nèi)容不是事實(shí)，也可能用陳述語氣：
I feel as if [as though] I’m floating on air. 他感到好像漂浮在空中。
The stuffed dog barked as if it is [were, was] a real one. 玩具狗叫起來像真狗。
(2) 注意 It isn’t as if…的翻譯：
It isn’t as if he were poor. 他不像窮的樣子(或他又不窮)。
It isn’t as if you were going away for good. 又不是你離開不回來了。
