World Clean-Up Day is an annual event that aims at (1) people’s awareness of the solid waste problem, and uniting countries around the world to take (2) in cleaning up the p

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World Clean-Up Day is an annual event that aims at (1) ________ people’s awareness of the solid waste problem, and uniting countries around the world to take (2) ________ in cleaning up the planet and finding solutions (3) ________ this problem.

with

about

Giải thích

Đáp án đúng là C

“Solution to a problem”: giải pháp cho một vấn đề. “Solution to + Noun” là cấu trúc cố định. “on, with, about” không dùng với “solution”.