What is the ratio of the length of the mining zone to the length of the bench?( )
A、Fulllengthorpartofit;
B、Fulllength;
C、Partofit;
D、None
发布时间:2025-11-02 03:39:46
A、Fulllengthorpartofit;
B、Fulllength;
C、Partofit;
D、None