The income of the common people has been greatly increased in the past thirty years the

问题补充：

The income of the common people has been greatly increased in the past thirty years the reform and opening-up policy in China.

A. regular; because

B. usual; thanks to

C. normal; on an account of

D. annual; owing to

答案：

A. regular; because

B. usual; thanks to

C. normal; on an account of

(答案→)D. annual; owing to

解析：考查形容词和词组：句意：因为中国的改革开放政策，在过去的30年里面普通人的年收入已经大大增加了。第一空填annual“每年的”， regular定期的，usual平常的，normal正常的，第二空除了C项应该是on account of，其他的： because thanks to owing to 都是因为，选D。