题干
Low-carbon lifestyle is of great benefit to improve the world environment．________can be enjoyed from it until you have a deep understanding of it, however．
A：Something
B：Nothing
C：Few
D：Much
答案(点此获取答案解析）
B
的c点有一固定绳圈。若绳圈上悬挂质量为m2的钩码，平衡后绳的ac段正好水平，则重物和钩码的质量比
为（ ）