求教:I go to school on weekdays,but not on Saturday and Sunday.

问题描述:

求教:I go to school on weekdays,but not on Saturday and Sunday.
I go to school on weekdays,but not on Saturday and Sunday.
请问上句中后半截是否定,为什么用“and ”而不用“or”呢?

"And"用于肯定句,其转换为否定形式为"Or",就像"Too"一样,都是规定了的.硬性规定的,只要And在作并联词时,在否定句中都要改成Or。