A lot of students study hard,Tom studies hardest.

问题描述:

A lot of students study hard,Tom studies hardest.
A lot of students study hard,and Tom studies hardest.哪一句对 两句中间都是逗号.

第二句对.要有and作为连词,因为英语的语法中不允许出现句子逗号句子的形式.