Question

It was in the classroom ______we had class meeting

Answer 1

填 that
这是强调句，不管强调的是事情、地点还是人物，引导词都要用that，不能用which, where 或who.
例句：
It is these photos that reminds me of the happy days at campus.
It was in the classroom that we had class meeting.
It was my grandparents that brought me up after my parents were killed in a car accidents when I was only four years old.

Answer 2

It was in the classroom __where____we had class meeting

Answer 3

that
这是强调句的句型
it is\was_that