—How long does Kitty spend on her homework?—.A. Half an hour B. A half hourC. Half hours D

问题补充：

—How long does Kitty spend on her homework?

—.

A. Half an hour

B. A half hour

C. Half hours

D. An half hour

答案：

(答案→)A. Half an hour

B. A half hour

C. Half hours

D. An half hour

解析：

试题分析:根据题干how long可知询问的是时间段，又根据选择项的提示可知就是半小时，在英语中半小时的表达方式就是half an hour，故选A。