Mr. Han, my neighbor, is always helping those who are in trouble without expecting anythin

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A. in turn
(答案→)B. in return
C. in detail
D. in addition
解析：这题考查词组辨析：in turn依次，in return做为回报，in detail详细的，in addition此外，句意是：我的邻居韩先生总是帮助那些有困难的人而不期望回报。选B。