请比较that在名词从句与定语从句中的区别：
1）在名词从句中，that不充当句子成分，所以that后面一定要接完整的陈述句。
2）在定语从句中，that一定充当句子成分，如作主语、宾语或表语，所以that后面接不完整的陈述句。
a. The rumor that he spread everywhere turned out to be untrue.
b. The rumor that Tom was a thief turned out to be untrue.
以上两句从句的先行词都是the rumor，连接词都是that。
但a句中的that在从句he spread everywhere中作成分，充当spread的宾语，故该从句为定语从句。b句中的that在从句Tom was a thief中不作任何成分。从句Tom was a thief是一个完整的句子，不缺任何成分，故b句为同位语从句，作the rumor的同位语，补充说明the rumor的具体内容。
c.The fact that we talked about is very important.（that作talked about的宾语，定语从句）
d.The fact that he succeeded in the experiment pleased everybody.（that不充当成分，同位语从句）
e.The fact that there are no lives on the moon is known to us all.（同位语从句）
f.The fact that you pointed out made me interested.（定语从句）
注意，f句可改写为：The fact which you pointed out made me interested.若是同位语从句，则不能把that换成which。