宾语从句的连接词做主语

问题描述:

宾语从句的连接词做主语
例句:we have to check what is in it .
为什么这里不用陈述语序

we have to check what is in it
这不还是陈述语序吗.it在这里是in的宾语,in it是介词短语做表语.
比一比
we have checked out that the cat is in it
它们是一样的结构