【一】宾语从句【1】They knew that he is a child.?变为一般问句：Did they know that he is a child?【正确】【2】He asked whether you need help.?变为一般问句：Did he ask whether you need help?【正确】【3】They've known why he hadn't come here.??变为一般问句：Have they known why he hadn't come here?【正确】备注：宾语为从句的时候，只需要主句一般疑问句，宾语从句表示不变。【二】表语从句【1】The fact is that he is a child.?变为一般问句：Is the fact that he is a child?【正确】【2】The question is whether you saw me.?变为一般问句：Is the question whether you saw me?【正确】【3】The problem is how we will go there.?变为一般问句：Is the problem how we will go there?【正确】备注：表语为从句的时候，把主句be动词提前到句首变一般疑问句。【三】主语从句【1】That he is careful is a fact.?变为一般问句：Is that he is careful a fact?【错误】更正：Is it a fact that he is careful?【2】Whether they will come is a question.?变为一般问句：Is whether they will come a question?【错误】更正：Is it a question whether they will come a question?【3】How we go there is a problem.?变为一般问句：Is how we go there a problem?【错误】更正：Is it a problem how we go there a problem.备注：that引导陈述分句作主语和wh-疑问词引导疑问分句作句中主语，变一般疑问句的时候需要使用外置主语结构，即使用形式主语it?，把真正主语放在句末。Warm prompt: ?The above answer,based upon my personal understanding, is only for reference.?