关于状语从句的几个问题

题目

关于状语从句的几个问题
You are from UK,but I thought you ____ American.
A.are B.have been C.were D.had been
老师说这是过去认为他是美国人,可是thought不已经是过去式了么?
--Perhaps I'm going to the market.
--Would you get me some juice _____ you're there?
A.since B.as C.if D.after
为什么不能用if?理解成“如果你到那儿,可以帮我带一点饮料么?”这样为什么不行?
还有,so做连词时的用法就是方式状语从句中so的用法么?so和so that 仅仅是so that引导的从句带有情态动词么?

答案

You are from UK,but I thought you ____ American.
A. are B.have been C.were D. had been
thought是用的过去式,you were American是做thought的宾语,宾语从句的时态要和株距保持一致.再有就是这个人本身如果是美国人的话,不管什么时候都用现在时态.
第二个题主要是因为第一个人已经说了他要去超市,所以第二个人就不应再假设了.注意语境的理解.