2、as if / though 引导的状语从句，时常用虚拟语气，表示与事实不符或相反的情况
He spoke in that way as if he were a foreigner. 他讲话的方式就好像是老外。
3、as + adj. + a + 可数单数名词 + as … ：as---as 像---一样：第一个as是副词，修饰形容词或副词的'原级;
第二个as是连词，引导比较状语从句。在否定句中也可以改为not as(so)---as-----.
The film was not as/so good as I had expected. 这部电影不如我预期的好。
4、be about to do sth…when… 正要干……这时…… when == at that time
I was about to leave when the manager called me back. 我正要离开时,经理叫住了他。