非限定性定语从句中的关系代词可以用that或者省略吗？

仔细看看我下面给出的内容，你就会看到你需要的：
The Attributive Clause ( I )
1. Definition （定义）
定语从句: 在复合句中,修饰某个名词或代词的从句叫定语从句。
被修饰的词称为先行词(antecedent )．
连接定语从句和先行词的词称为关系词。

2. 关系词：
关系代词(relative pronoun):
who,that ,which, whom,whose 作主语／宾语 / 定语
关系副词(relative adverb): when, where ,why 作状语

3. 关系词的作用
1）连接作用
2）替代作用
3）成分作用
Madame Curie is unforgettable because she is the first female who /that won the Nobel Prize.

4.关系词的选用
关系词的选用是依据先行词在定语从句中的所充当的成分来确定的。
Madame Curie is unforgettable because she is the first female who /that won the Nobel Prize.
Madame Curie is unforgettable because she is a scientist whose discoveries are very important
Madame Curie is unforgettable because she is a scientist whom/that we can learn much from.

Things / places
The Internet is unforgettable because it is a thing that/which has greatly changed our way of life.
The Internet is unfor