1、关联词不能省略
2、从句用陈述语序
常见引导词
what, when, where, why, whether, how, that, because, which,
What surprised me most was that he spoke English so well.
The question is how what youve said can be put into practice.
The reason (why ) he didnt come is that he was ill.
It (This , That) is because iron contains more carbon than steel.