宾语从句连接词用法宾语从句中什么时候用that,what,which…………等等这些连接词（不是只有这三个,所有常用的连接词）,搞不懂在什么时候用什么连接词啊.举例说明,（不要百度百科的,看过了）

that引导表示陈述句的宾语从句,而if和whether引导表示“是否”的宾语从句.

that + 宾语从句 表 陈述一件事情
I think ,consider,believe,admit that sth happened,somebody did sth
what 什么
I don't know what you are trying to show
干什么
which 哪一个
I am confused which girl I should choose.
whom
I need to know whom I should ask.人称代词,宾格,在宾语从句中做宾语从句的宾语
why 为何
I was not aware why this happedn
how
Let me know how this come up with.
怎样