In the U.S.Mother's Day is a holiday celebrated on...(有关celebrated)

问题描述:

In the U.S.Mother's Day is a holiday celebrated on...(有关celebrated)
In the U.S.Mother's Day is a holiday celebrated on second Sunday in May.
请问这句话不是一般现在时吗?为什么celebrate + d

被动语态啊/
因为holiday 是被celebrated