Mr Li who is in charge of our class is very experienced.A. theB. aC. /D. an

问题补充：

Mr Li who is in charge of our class is very experienced.

A. the

B. a

C. /

D. an

答案：

A. the

B. a

(答案→)C. /

D. an

解析：考查冠词：这题也是固定词组：sb be in charge of sth某人负责某事，如果是某事被某人负责，就用sth be in the charge of sb，句意：负责我们班的李老师是很有经验的。选C。