“Where did you find the professor who made the speech yester

选A,而where和which的区别就在于它们在定语从句中充当的成分,where是副词,所以当的是状语（地点状语）,定语从句中的意思应该是 the students often have a meeting in the hall,缺in the hall地点状语,所以用where.而which是代词,在句中充当的是名词所充当的成分,和句意 不符嘛.再来是that,如果是that,那就是It was/is .that ...,你知道是强调句的（当然也有可能是定语从句,若是定语从句,在此题的解释和which一样）,如果是强调句来看的话,整个句子结构上是没错,不过问句问的是where,那么你就要用相应的成分来回答,而不是回答一个这样的句子.当然可以用强调句回答,只是那么就应该是类似这样：It was in the hall that I found him.