是on Mothers Day.英语时间的用法为:in年in月in季节,如in 2023, in May, in summer;at加时间,如at 6six oclock, at half past ten; on在详细日子前,如on Monday, on June second, on Teachers Day。
“在母亲节那天”是详细的日子,故此,要用on。差不多节日都是用ON 的,,,,也有例外,春节,at Spring Festival英语"祝你母亲节快乐"?肯定是Happy Mothers' Day! 因为mother 是全部母亲,故此,应该Happy Mother's Day Happy Mothers' Day 母亲节快乐!