英語中which引導什么從句

　　There are two points which I wanted to make.

　　我想要指出的有兩點。

　　We are still friends, though, which is good.

　　不過我們仍然是朋友，這令人感到欣慰。

　　Which part of Japan do you come from?

　　你是日本哪個地區的人？

　　There is some noise in the data which needs to be reduced.

　　資料里有一些需要刪除的不適用信息。

　　Which is the largest city in the world?

　　世界上最大的城市是哪個？