Was it through Mary was working at a high school you got to know Tom?A. who; whoB. that;

问题补充：

Was it through Mary was working at a high school you got to know Tom?

A. who; who

B. that; which

C. who; that

D. who; which

答案：

A. who; who

B. that; which

(答案→)C. who; that

D. who; which

解析：考查定语从句和强调句型。本题第一空是定语从句，先行词是Mary，关系代词who指代先行词在句中做主语。第二空中的that与it was构成强调句型。句意：正是通过在高中读书的Mary，你才认识Tom的吗？第一空可以使用that/who，但是为了避免和后面的that重复，所以使用了who。故C正确。