储量级别
参考答案：区分和衡量储量精度的等级标准。我国煤炭储量按精度依次为A，B，C，D四级
—Tony said he could fix my bicycle, but I really doubt it.
—_______. He’s very good at this sort of thing.[ ]
A. Don’t worry
B. I couldn’t agree more
C. Of course
D. A piece of cake
当作业高度是12米时，发生坠落后造成人员死亡的概率是（）。
A.25%
B.50%
C.75%
D.100%
