各位版友好，想请问一下，
在柯林斯词典看到这样的解释：
idiom N-COUNT
An idiom is a group of words which have a different meaning when used
together from the one they would have if you took the meaning of each word
separately.
1.when used together 是不是可还原为 "when they are used together" ?
2.from the one they would have 该如何理解？the one可以理解成
"the meanings of the individual words"吗？
the one (that) they would have的意思是
they would have the meanings of the individual words 吗？
请教了，谢谢！