英语什么情况下节日前不加定冠词?

一般以 Day 结尾的节日和一些西方传统节日前，都不加冠词
May Day
Mother's Day
Children's Day
Father's Day
National Day
Easter
Christmas
Halloween
Thanksgiving Day
一般以Festival 结尾的节日前要加定冠词 the
the Spring Festival
the Dragon-Boat Festival