分析2个句子的语法

第一个是定语从句，拆成两个句子你就明白了：
I like to visit a place. 和 The place's history is long.
所以whose代替了the place's

第二个句子中，因为主句用了过去式didn't know,所以宾语从句的时态相应往过去移一个时态，过去的过去，所以从过去式变成了过去完成时。
We don't know what happened in the shop.
---We didn't know what had happened in the shop.

1. whose = the place's
2.过 去 完 成 。 Otherwise, "what was going on".

1.定语从句
WHOSE修饰PLACE，表示这个地方的历史悠久

2.因为前半句是过去式，后面是宾语从句，表示在主语之前的事情，所以用过去完成时。

I like to visit a place whose history is long．

定语从句,whose做关系代词

We didn't know what had happened in the shop

宾语从句,从句必须是一个完整的句子,shwt 是主语.由于主句用的是过去时,从句就用过去完成时,had happened.