There are advertisements which encourage to participate in improving their neighbourhood.A

问题补充：

There are advertisements which encourage to participate in improving their neighbourhood.

A. the public,the public

B. the public,public

C. public,public

D. public ,the public

答案：

A. the public,the public

B. the public,public

C. public,public

(答案→)D. public ,the public

解析：词形辨析。句意：有公益广告鼓励公众参与改善社区的活动。结合语境可知前文为形容词作定语，下文为名词，特指某些公众，用定冠词。故选D。