when

When did the first human land on the moon?

(Chinese) 人类第一次登月是什么时候？

Could you tell me when the next train to London arrives?

(Chinese) 你能告诉我去伦敦的下一班火车什么时候到达吗？

The alarm goes off every morning when the sun begins to rise.

(Chinese) 每天早晨太阳升起时，闹钟就会响起。

I will call you back when I finish my dinner.

(Chinese) 我吃完晚饭后会给你回电话。