Lei Feng is always ready to help others when they are in trouble and he never their reque

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A. turns up
B. turns over
C. turns in
(答案→)D. turns down
解析：本题考查短语动词的区别。turn up的意思是“将音量调高”、“出现，露面“；turn over意思是“打翻，移交；翻身”；而turn in表示“上交”；turn down表示“将音量等调低或拒绝”的意思。结合上下文的意思应该选D。