Question

请问这句是定语从句吗?

第一题是 It is hard for me to show kindness to people that hate me.
如果简化就是 They show kindness to people that hate me.
如果是定语从句 that 可以改为 who吗? that 可以代替who充当主语是吗?

第二题
This truth is so well fixed in the minds of the surrounding families, that he is
considered the rightful property of some one or other of their daughters.
这句是定语从句吗?

It is a truth universally acknowledged, that a single man in possession of a good fortune, must be
in want of a wife.
请问这个that前面为什么用 ，呢??? 这句好像也是定语从句...

Answer 1

第一题：
注意：They show kindness to people that hate me 不是 It is hard for me to show kindness to people that hate me 的简化。这是两个不同意思的句子。你再仔细看看。
They show kindness to people that hate me 中的 that 可以用 who 替换。这里的 that 或 who 不是充当主语，而只是引导从句的关系代词（指代从句主语），真正的主语是从句所修饰的先行词。

第二题：
是的，that 从句是一个同位语定语从句，修饰 families。但是，that 前面的逗号用得不好，应该去掉。或者，将 that 换成 which，这个从句就是一个非限定性从句，进一步说明 主句。

It is a truth universally acknowledged, that a single man in possession of a good fortune, must be
in want of a wife.
这一句中的两个逗号都用得莫名其妙，应该去掉。其实，这一句中的 that 从句更确切地说是这句话的逻辑主语。前面的 It 只是一个形式主语。

Answer 2

that is very lovely.是定语从句，其修饰的先行词是dog。
that是连接代词，在从句中主语。
l like the dog that is very lovely.（我喜欢那条非常可爱的狗。）