5、词性从句时,不在句子中做成分,不含疑问意义,也没有实际意义,只起连接作用,在句首时不可以省略。what在引导名词性从句时,既起连接作用,又在从句中做主语或宾语,在任何情况下都不能省略,它有具体意义,相当于all/everythingthat。I think__________he will be back in a week.__________ he said is true.I really don’t know __________he is doing.__________hewonthefirstprizemadehisclassmatesexcited.练一练