都有下面的集中情况:1.当先行词为anything,everything,nothing等不定代词时,只能使用“that”。例:Is there anything that I can do for you?(我能给你做点什么吗)
2、当先行词为all,any,much,many词时,只能使用“that”。例:Tom told her mother all that had happened.(汤姆把事情的全部情况告诉了他的妈妈。)
3、当先行词是形容词最高级或被形容词最高级修饰时,只能使用“that”。例:This is the most wonderful time that I have ever had. (这是我度过的最美好的时光。)
4、当先行词是序数词修饰时,只能使用“that”。例:He was the first person that passed the exam.他是第一个通过考试的人。
5、先行词被the only,the very,the same,the last修饰时,只能使用“that”。例:This will be the last chance that he can get.(这将会是他得到的唯一机会。)
He is the only person that can help you out.(他是唯一能帮你的人。)
6、先行词里同时含有人或物时,只能使用“that”。例:They talked of things and persons that they remembered in the school.(他们谈论他们记得的有关学校的事和人。)
7、当主句是以who,which开头的特殊疑问句或先行词是who时,只能使用“that”。例:Which is the book that he bought from the library yesterday?(哪本是你们昨天从图书馆借的书)
从属连词只用that的情况
1】and连接两个宾语从句,that宾语从句放在and的后面时,that不能省略。 Eeveybody could see what happened and that Tom was frightened.这里动词see 有两个宾语从句 1是 what happened 2是 Tom was frightened规则说,这种情况的 and 后面的 that 不可以省略。-------像这么解释你觉得可以吗 如果可以我再补充,我说不上来更详细的了。