in which的用法这里有一句and then they're going to go on a world tour in which they will perform in ten different cities.我还记得以前有个什么在结尾在in的可以放到前面来也是成为in which,不过我不知道这里后面哪里可以用in能把他的用法详细地说明一下么？听不太懂啊

相当于地点的就可以啊，给你几个例句 啊！！
1.I am looking at the picture in which my grandpa smiled happily.
可以还原一下啊！My grandpa smiled happily in the picture.I am looking at the picture.

这是英语的常规的用法,很常见的,相当于
They will perform in ten different cities in a world tour,which they're going to go on.
There are several ways in which this may happen. ==
There're several ways which this may happen in.
你可以把in把到后面,不过最好还是遵守常规用法.

就是先行词在从句中in的宾语时用in which 嘛,你搞得这么复杂做什么.
I live in a lovely world.
the lovly word in which I live .
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不用说细说,因为说穿了很简单:任何做in 的宾语 的词都可以改成in which定语从句.
Bejing is a big city.I was born in Bejing.In Bejing
Being is a big city in which I was born.