“制动波速”与制动波传播长度和传播时间有关。
参考答案：对
钻进时，出现煤岩松软、片帮、来压或钻孔中的水压、水量突然增大，以及有顶钻等异状，必须停止钻进，立即拔出钻杆
Actually, much of what was being presented on the stage at that time was () and experimental.
A. positive
B. negative
C. sensitive
D. innovative
