立井提升的任务是沿井筒提升（）等。
A.煤炭、矸石
B.下放材料
C.升降人员
D.设备
参考答案：A, B, C, D
_____, you'll never be able to persuade him. [ ]
A. However hard may you try
B. However hard you may try
C. However you may try hard
D. Try hard however you may
通过拉伸试验可以得到金属材料的3个强度指标是弹性极限、（）和抗拉强度。
A.屈服点
B.疲劳强度
C.冲击韧性
D.硬度
