在井筒内用罐笼运送硝化甘油类炸药或电雷管时，罐笼的升降速度不得超过（）m/s。
A、2
B、3
C、4
参考答案：A
Every group of human beings has ______.
A．its own set of ideas, beliefs and ways of life
B．an extremely complex and delicate language
C．its own elegant music, literature, and other arts
D．the process of growing crops or raising animals
指明目标原理
