which一般引导什么从句

　　I'd forgotten the keys, which didn't help matters.

　　我忘记带钥匙了，这让情况更糟。

　　They all look so alike to me that I'm never sure which is which.

　　它们在我看来简直一模一样，我永远分不清哪个是哪个。

　　Which direction are you facing?

　　你面朝哪个方向？

　　Which planets can sustain life?

　　哪些行星可以维持生命的存在？

　　Show me which picture you drew.

　　指给我看哪张画是你画的。