—What about the student in your class, Mr. Wang?
—The doctor said that sleep caused him poor memory and poor concentration.
A. lacking of
B. lacked in
C. lacking
D. lack for
网友回答
A. lacking of
B. lacked in
(答案→)C. lacking
D. lack for
解析：考查lack的用法。根据句子结构可知此处 sleep 作caused的主语，故选择lack的名词形式或者动名词形式。排除B.lack作名词时用法为lack of,排除A，D。 故选择C