In the United States there is always flow of people to areas of country where more job

问题补充：

In the United States, there is always flow of people to areas of country where more jobs can be found.

A. a; the

B. the; a

C. the; the

D. a; a

答案：

(答案→)A. a; the

B. the; a

C. the; the

D. a; a

解析： a flow of people 指“流动的一群人”，the country 特指前面的the United States.