All the photos__were taken during the trip are very beautiful

__were taken during the trip 是定语从句 修饰All the photos 因为有All所以只能用 that 像everything everybody nothing 等也是一样的规则

因为all the photos是个固定搭配么，“所有的照片”。
它在句子中做的是宾语~
当定语从句中有all very 等词出现时`只能用that

因为先行词中有all，所以用that
以下是用that和which的情况

在定语从句中，关系代词that和which指物时，一般没有区别，但下列几种情况中不能互换：
1 只能用that的情况：
a)先行词为all,everything,nothing,anything,little等不定代词时（something后也可用which）：
Is there anything (that) I can do for you in town?
That’s all (that) I know.
b)先行词被序数词所修饰时：
The first thing (that) we should do is to work out a plan.
c) 先行词被形容词最高级所修饰时：
This is one of the most exciting football games (that) I have ever seen.
The nanjing yangtse river bridge is the longest bridge (that) they have ever seen.
d)先行词 被only,very,no,any,same,little,one of等词所修饰时：
This is the only thing (that) we can do now.
He gave me the same pen (that) he borrowed from me.
Do you have any books that were written by Lu Xun?
This is the v