定语从句先行词是名词或代词时,联系词都可以是that吗?

不是的,
习惯上不用that引导的定语从句
(1)在非限制性定语从句中,不以能用that引导.
Yesterday I met Mary, who seemed very excided. 昨天我碰到了玛丽,她显得非常兴奋.
(2)直接在介词后作宾语时,不能用that引导,要用whom, whose或which,且不能省略.
The house in which we live is not large. 我们住院的房子不大.
I know the young man with whom you live. 我认识和你住在一起的那个年青人.
但当介词放在从句的末尾时,可以用that替代which, who替代whom,也可以省略关系代词.如：
The house (which/that) we live in is not large. 我们住院的房子不大.
I know the man (whom/who/that) you live with. 我认识和你住在一起的那个人.
(3)当先行词是指人的all, any, few, one(s), anyone, everyone, those, people, he等时,只能用who.
None so blind as those who won't see. 睁眼不看事实的人眼最瞎.
Anyone who is over sixteen is allowed in. 任何超过十六岁的人都允许进去.
I met someone who said he knew you. 我碰到一个人,他说认识你.
He who has a mind to beat his dog will easily find his stick. (谚)欲加之罪,何患无辞.
(4)当先行词与关系代词之间有较复杂的短语或从句隔开时.
I was the only person in my office who was invited. 我是我们办公室里唯一受到邀请的人.
A new master will come tomorrow who will teach you German. 有位新校长明天来,他将教你们德语.

当然 你大概是把which 和that这点弄混了吧
在先行词为不定代词的时候 可用that不能用which 如All that can be done has been done. All为不定代词知道吧?
还有就是在非限制性定语从句中是不用that表示“什么”的意思的 不知道你有没有上高一 上了高一学了就明白了 要先还没就不要先计较我说这个哈. 非限制性里“什么”的...