为什么你今天没来上课？

___Why didn't you come to class today?

哎呀，你怎么把蛋糕全吃光了！

___What, you ate all the cake!

我们为什么不去看电影呢？

___Why don't we go to the cinema?

这就是我为什么如此喜欢这座城市的原因。

This is ___why I love this city so much.