Research shows that humans from selfish to unselfish behavior when they are watched.
A. tell
B. switch
C. range
D. distinguish
网友回答
A. tell
(答案→)B. switch
C. range
D. distinguish
解析：A. tell辨别，B. switch转换，C. range在…范围变化，D. distinguish区别，句意：研究表明人类当被注视的时候，会从自私的行为转变成无私的行为。所以选B。