Then moment Mary will always remember is Mr. Black gave her a lot of valuable advice on

问题补充：

Then moment Mary will always remember is Mr. Black gave her a lot of valuable advice on how to improve her writing.

A. when; that

B. that; that

C. that; when

D. when; where

答案：

A. when; that

B. that; that

(答案→)C. that; when

D. when; where

解析：考查定语从句。第一空考查定语从句，先行词为moment，在定语从句中作宾语。第二空是由when引导的表语从句。句意：那时玛丽总记得的时刻是当布莱克先生在关于怎么提高她的写作给出许多宝贵的建议。故C正确。