请教“What do you do at Christmas"这里的介词为什么用at 而不是用on?

What do you do at 请教“What do you do at Christmas这里的介词为什么用at 而不是用on? 英文翻译What do you do at the What do you do at the weekend? What subjects do you do at school? what do you do at break time? what do you do at your birthday? what can you do at what do you draw at what do you do at break time what do you do at break time 是 What do you do at the weekend 还是What do you do on the weekend what do you do? “what do you do! What do you do? what do you do What activities do you ( ) at your school? What can you do at home? What ( )do you have at your school?