定语从句中 who和 that的问题

问题描述:

定语从句中 who和 that的问题
有这么个句子:
Mary received a call from Peter () dated when she was in high school.
句子里的空格,填that还是who或者whom?
感觉后两者可以,that填进去很别扭,至于为什么,
括号后面应该还有个she,不好意思

因为一般都爱说 Peter was the person that I dated.
所以说用that的时候习惯放在没有确定人名的情况下,而有了准确的人名就用who/whom好点.
还有楼上的说的不对,估计没明白DATE是什么意思