分类：教育/科学-学习帮助
问题：English~~~~~~~~~________whohewas 
________who he was ,the guard regard the new mayor as one of the visitors .A) Not having known B) Knowing not C)Having not known  D) Not knowing  选A还是D 为什么?
回答：选D  这是一个因果从句,并且前后要求主谓一致,因主句的主语是人,是动作的发出者,所以从句用主动形式,否定词NOT应放在句首,又因为把从句补全是because he didn't know who he was 而不是 because he hasn't know...并且,主句时态是过去时,就算用have也应用 had .