in which中的which是指代前面的东西,which可以指代地点也可以是时间,也就是说前面的先行词只要是可以和in搭配的就可以,比如说先行词是house,你是in the house你就可以in which,这时候因为是地点所以可以和where换用.
例如,He finally chose to leave the house in which he had a lot of beautiful memories.
这边的in which也可以用where来替代.
又比如.Galileo's ideas were well in advance of the age in which he lived.这边的age是时代的意思,是时间,也可以用when来代替.