关于定语从句的问题

Question

1.先行词that在什么情况下可以省略？
2.碰到“地方”的，有时用where，有时用which，怎么分？
3.where,when,which属什么词性？
4. 碰到"day"时，有时用when，有时用that，怎么区分？
第4题的确要举个例才行：He still remembers the days______(that or when)he spent with your family.
还想问问：是不是when 和where都是用在主谓宾齐全的情况下？

Answer 1

1、当THAT在定语从句中充当宾语的时候可以省略
2、看定语从句中的动词，如果那个动词是不及物的，那它后面肯定带了一个介词，这个时候要用WHICH，因为WHERE是副词，副词前面不能加介词
3、WHERE是副词
WHICH是代词
WHEN是时间代词
4、这里用THAT，因为DAS和HE SPEND WITH HIS FAMILY之间没有修饰关系，它们2个指的是同一件事就是和家人在一起的时光，而后面的句子只是进一步解释说明THE DAYS，所以这里是一个同位语从句，并不是定语从句 。

关于括号里面的问题，一般情况下通常是这样的。

Answer 2

当定语从句修饰的是不定代词all, anything, little, everything, nothing, something时:
There is little that I can do for you.
I can’t remember anything that he said.
I have nothing that is more valuable than our friendship.
This is sth that I want to tell you
当定语从句修饰的名词前面有形容词最高级作定语时:
This is the best film that I have ever seen.
The highest mark that I got was100 in physics.
当定语从句修饰的名词前面有序数词或only,last :
You are the only person that can help me.
This is the first book that I read.
He was the last one that arrived at school today.
2、看定语从句中的动词，如果那个动词是不及物的，那它后面肯定带了一个介词，这个时候要用WHICH，因为WHERE是副词，副词前面不能加介词
3、WHERE是副词
WHICH是代词
WHEN是时间代词
4、He will remember that day when (on which) he got the highest mark in his physic exam.
It was in the morning when the earthquake happened.(只能用when)