as if, as though的用法
as if 与as though 是一组同义词，两者意思相同，用法也相同，只是在口语中人们多半会用as if, 取其简短。As if/as though 结构中的动词形式通常决定于说话人的语义意图。试比较：
I feel as if I was/were going to faint. (我感觉好像要晕倒了)
I feel as if I am going to faint. (我感觉真的就要晕倒了)
He walks as if he is drunk. 他已经醉了
He walks as if he were drunk. 他没有醉
It looks as if it is going to rain. 快要下雨了
It looks as if were going to rain. 不会下雨
这就是说，在某些语境中，如果不表示假设意义，就不必用过去时形式。也就是说，如果a
s if后面的从句所表示的情况时真实的或很可能时真实的，则动词可以用陈述语气，在feel, look, em, smell, sound, taste之后尤其如此。例如：
There’s Hob, talking to the ticket-collector. It looks as if he hasn’t got a platform ticket. 那不，霍布正在同检票员说话，看样子还没弄到站台票。
It looks as if it is going to rain. It ems as if we will have to go home on foot.
You look as if you’ve been running. 你好像刚跑了一阵似的。
You look as if you know each other. You have acted as if you like me.
The fish smells as if it has gone bad. The apple tastes as if it is sour.
He looks as if he’s tired. It looks/ems as if you’re right.
It smells as if it is fresh. 闻起来很新鲜。
It looks as if it hasn't been washed following the instructions. 看来，它（这件衬衫）好像没有被按照说明进行洗涤。
It emed as if the bag had been presd by something heavy. 看来这个包被什么重东西压过。
It emed as if the suit was made to his own measure. 这套西服看上去是按他的尺寸订做的。
1．在通常情况下， as if 和as though 所引导的从句的谓语动词多用虚拟语气，表示所叙述的情况与事实相反。具体用法如下：
1)谈论现在情形的，用过去时（动词be用were,也可用was）：
Why is she looking at me as though she knew me? 他为什么那样看我？像是认识我似的。
He behaves as if he owned the hou. 他的样子好像他拥有这个房子。
He treats me as if /as though I were a stranger.
He speaks as if he were an Englishman.
It’s not as though he was /were poor.
2)谈论过去情形的动词形式有以下几种：
a)过去式，表示过去的状态，如：
He looked at me as if I were mad. 他那样看我，好像我是个疯子。
He stood there looking at the train and laughing, as if to miss a train was the best joke in the world.他站在那里，望着火车哈哈大笑，好像误了火车是天底下最开心的事儿似的。
Mr. Coleman always talked as if he knew everything.
Holding his head high, he walked past the pole and the soldiers as if they didn’t exist.
但是，如果状态动词带有持续时间状语，则用过去完成时：
They talked as if they had been friends for years.
(试比较：They had been friends for years.)
Now it is as though she had known Millie for years.
情态动词亦用过去时：
She felt as though she could hardly endure such a life.她觉得简直无法忍受这样的生活。
b)过去完成时，表示过去的动作先于主句动词而发生或完成，如：
It was as if he had lost his last friend.
“I remember,” she tells her children now, “how wild his white hair looked——as if it had been electrified.”
必须注意的是，在指过去的动作时，即使主句是现在时，as if 从句中的动词也要用过去完成时：
You look as if you’d en a ghost. 你好像是见了鬼似的。
He talks about Rome as though he had been there himlf.他讲起罗马的情况来就好像他亲自到过那里似的。
c)过去进行时，表示动作正在进行：
He heard a noi, as if someone was breathing.
He ran as if ghosts were chasing him.
I felt as if the ground were slipping beneath my feet. 我感到大地仿佛在脚下滑动。
d)过去将来时，表示将要发生的事态：
It looked as if it was going to snow.
He opened his lips as if he would say something to you.
特别注意：as if 引导的同一从句中所用的时态不同，意思往往不同。请比较：
* The clown looks as if he were ill.那个小丑好像害病似的。（虚拟语气）
* The clown looked as if he had been ill.那个小丑过去好像生过病。（过去生过病或虚拟语气）
此外，It isn’t as if…的翻译。如：
It isn’t as if he were poor. 他不像穷的样子(或他又不穷)。
It isn’t as if you were going away for good. 又不是你离开不回来了。
2. 随着语言的发展，as if后面的从句即使反映的不是事实，也可以不用虚拟语气而用陈述语气，这主要出现在口语或不太正式的文体中。例如：
With the development of the new tools, it is as if man has suddenly become a millionaire of the mind.随着这些新工具的发展，人好像突然间成为精神上的百万富翁似的。
Teenagers may talk as if they know it all, but statistics tell a different story.
The “historical prent” is sometimes ud in narrative when we want to describe events vividly as if they are happening in our prence.
3. 在非正式文体（尤其是美国英语）中，可以用like做连词代替as if 和as though。例如：
It looks like it’s going to rain today.
She looks like she’ll win the race.
I love that boy like he was my son.
He looked like he needed someone to talk to, so we lent him an ear.
He sat there smiling like it was his birthday.
She started kissing me like we were on our honeymoon.她开始吻我，好像是在度蜜月似的。
4. as if和as though从句中的省略
当as if和as though从句的主语与主句一致时，该主语和后面的动词可以省略。于是便出现下面几种结构：
1) as if +不定式
He opened his lips as if (he were) to make some reply.
The bee checked its forward speed, circled and then drifted slowly over the mirror like surface of the pool as if to admire its own reflection. 蜜蜂放慢飞行速度，转了几圈儿，然后在清澈如镜的水潭上空慢慢地飘过，似乎要欣赏它自己的倒影。
