问题补充：
Was it through Mary was working at a high school you got to know Bob?
A. who; who
B. who; that
C. that; that
D. that; where
答案：
A. who; who
(答案→)B. who; that
C. that; that
D. that; where
解析：第一空考查定语从句，先行词Mary关系词who在从句中做主语；第二空考查强调句型it is +被强调部分 +that….。句意：就是通过工作在中学的玛丽你认识鲍勃的吗？
