句型连接词例 句说 明时态语序主语从句thatThat he will come is certain.that在句首不可省去主语从句中只能用whether，不可用if主语从句放在句首，句子常显得笨重，因此一般把它移到句子后面，前面用引导词“it”来作形式主语。1. 主句是一般现在时，从句根据实际情况使用任何时态。2. 主句是过去时态，从句须用过去时态的某种形式。3. 当宾语从句表示的是一个客观真理或者事实时，即使主句是过去时，从句也用一般现在时态。陈述句语序注意Whatswrongwithyou?Whatsthematterwithyou？Whats the trouble with you？whetherWhether there is life on the moon is an interesting question.Who，what，which，whoeverWhat he wants to tell us is not clear.When，where，why，howWhy he didnt come is not clear.宾语从句thatI believe(that) he is honest. whether常与or not连用，不能用if代替。作介词宾语要用whether不能用if。如果宾语从句后面有宾语补足语，则用it作形式宾语，将从句后置。think, believe, imagine, suppose等动词引出的宾语从句，要将从句中的否定形式，移到主句中。if，whetherI wonder whether he will come or not.who, whom, which, whose, what 及其ever 形式Please tell me what you want.when, where, why, how,Tell me where you have gone.表语从句thatThe trouble is that we are short of hand.在非正式的文体中that可以省去。表语从句位于主句系动词之后whetherThe question is whether we will come here or not.as ifIt looks as if its going to rain.who, what, whichThats just what I want.when, where, why, howThat is why he didnt come to the meeting.名词性从句主语从句：宾语从句：表语从句：