Recently there is boom（繁荣）in population mobility and according to national population s

问题补充：

Recently, there is boom（繁荣）in population mobility and according to national population survey of , 17 percent of the population move every year.

A. the; a

B. a; the

C. /; a

D. the;/

答案：

A. the; a

(答案→)B. a; the

C. /; a

D. the;/

解析：考查冠词。第一空a boom泛指在人口流动方面的一次繁荣，故用不定冠词a；第二空the national population survey of 是特指的的国家人口调查，故用定冠词the。句意：最近根据国家人口调查，人口流动方面有一次繁荣，每年有17%的人口流动。故B正确。