Where were you yesterday?为什么没有介词?

问题描述:

Where were you yesterday?为什么没有介词?
Where were you yesterday?请问这句话有错吗?问你昨天在哪,这句话为什么没有介词?at之类
那Where are you?这句话成立吗

【两句都正确】;
【yesterday】作时间状语,【Where】为疑问副词,故【不需加介词】.第二句亦【正确】,句末没有时间状语,由句意可知此句时态为【一般现在时】,对比【Who are you】.第二句为【一般过去时】.