as引导时间状语从句的谓语特点

as引导时间状语从句的谓语特点
 
■as 引导时间状语从句表示“当……的时候”“在……期间”时，该从句的谓语通常是那些表示动作意义的动词，而不能是be(是、在), have(有)，like(喜欢)，belong(属于)等表示状态或静态意义的动词。
我打算去邮局。——当你在邮局的时候，请帮我买几张邮票好吗?
误：I’m going to the post office.—As you are there, can you get me some stamps?www.34en.com
正：I’m going to the post office.—While you are there, can you get me some stamps?
■正因为 as 引导时间状语从句表示“当……的时候”“在……期间”时，从句的谓语不能是表示状态或静态意义的动词，所以当下面第一句变为第二句这样的状语从句时，不能再用 as，而应用 when：
As a student he had known great poverty.
＝When he was a student he had known great poverty. 他当学生时，经历过很贫困的生活。
■但是，当 as 引导原因状语从句时，其谓语动词可以是状态或静态动词。如：
As there was very little support, the strike was not successful. 由于支持的很少，罢工未获成功。
As I was anxious to please him, I bought him a nice present. 因为我急于讨好他，我给他买了一件精美礼品。
As there isn’t anything more to do, I may as well go home early 既然这里没有别的事要做，我还不如早点回家。