人类社会与动物社会的本质区别是（）。
A、语言
B、思维
C、劳动
D、直立行走
参考答案：C
加负反馈后的电压放大倍数减小了，但可使放大器的通频带得到展宽。
Even though his friends like to ___ him,he never takes it seriously. [ ]
A. make up for
B. make out of
C. make fun of
D. make most of
