at Christmas对还是on Christmas对?为什么?

at Christmas对还是on Christmas对?为什么? on christmas 还是at christmas 是on Christmas还是at Christmas? on Chritmas 还是 at Christmas? at christmas为什么不用on 为什么Christmas 前加at,Christmas day前加on We get Christmas cards at Christmas Day.对Christmas cards提问 at Christmas eve or on Christmas eve at christmas on Christmas Eve对吗? on christmas day?还是 in Christmas day? while christmas 还是while the christmas,为什么 They had a party on Christmas Day.对划线部分提问.（划线的是on Christmas