This is the room ---- they had a meeting last year.A.that B.

答案选B.where
1）主句为This is the room,定语从句____ they had a meeting last year为定语从句,修饰主句的表语the room.
2）根据定语从句的语法,可以将先行词the room放入定语从句中去,则为：
they had a meeting in the room last year
= in the room they had a meeting last year
= in which they had a meeting last year
= where they had a meeting last year
3）明显可以看出,应该用in the room做该定语从句的地点状语,所以应该选用关系副词where = in which = in the room.
4.而关系代词that/which只能代替先行词the room,但是the room不能单独在该定语从句they had a meeting last year中充当地点状语,所以答案AC错误.
而D what根本不能用于引导定语从句.