The government has taken measuresair quality.A. to improveB. improvedC. being improvedD. t

问题补充：

The government has taken measuresair quality.

A. to improve

B. improved

C. being improved

D. to be improved

答案：

(答案→)A. to improve

B. improved

C. being improved

D. to be improved

解析：考查不定式做目的状语：句意：为了改善空气质量，政府已经采取措施了。这里用不定式做目的状语，选A。