Another factor contributing to happiness is______.
A.highways
B.democracy
C.higher education
D.unpolluted water supply

A.A.highways
B.democracy
C.higher
B.unpolluted

【参考答案】

B
解析：本题为细节题。解题的依据是文章的第二段。选项A．highway和选项D．unpolluted wate......

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