1、用that引导: I'm sure (that) she will come.
2、用whether/if引导:表"是否"(但if不可放在句当"是否")
I don't know whether it will be fine tomorrow.
3、用疑问词引导(what,when,where,which,how,who,whose,why):
He didn't understand why they were laughing.
Do you know who is he?
Do you know where are they going?
Do you know what are they doing?
Do you know which girl is Lucy?
Do you know why he is late for class?
Do you know whether/if it will be sunny tomorrow?
Do you know how to make a model ship?
Do you know when Lucy will come back?
注意事项：
许多带复合宾语的句子，that引导的宾语从句经常移到句子后部，而用it作形式宾语。
例句：I find it necessary that we should do the homework on time.
（二）由whether,if 引导的宾语从句
由whether(if)引导的宾语从句，实际上是一般疑问句演变而来的。意思是“是否”。宾语从句要用陈述句语序。一般说来，在宾语从句中whether与if可以互换使用，但在特殊情况下if与whether是不能互换的。
例句：I wonder whether(if) they will come to our party.
只能用whether，不能用if引导的宾语从句
在带to的不定式前
例句：We decided whether to walk there.
可以的。
宾语从句，是名词性从句的一种。在主从复合句中充当宾语，位于及物动词、介词或复合谓语之后的从句称为宾语从句。宾语从句分为三类：动词的宾语从句，介词的宾语从句和形容词的宾语从句。
宾语从句相对比较简单些，
e.g.：
我觉得当时我错了。
我认为那对我来说不公平。
我们认为那是一个可行的计划。