简介： 二、单项选择（共15题，每题1分，计15分）
( )21.---:My son seldom has ______breakfast.
----: It’s______unhealthy habit.You must ask him to change it.
A. / , a B. the, an C the ,a D / , an
( )22.When I was young，I _______ in the country.
A. used to live B. was use...