煤层顶底板注浆作业，注浆结束的标准泵量应控制在每分钟（）以下。
A.100L
B.50L
C.80L
参考答案：C
发生霍乱时，对疫区内接触者，规定的隔离观察时间是（）
A．3天
B．5天
C．7天
D．10天
E．14天
A VLCC (100，000 DWT+) with a 30，000 Shaft Horsepower Steam Turbine is slow to respond to engine movements and has less stopping power than normal ships because it has a（）.
A.bigger propeller
B.smaller power to weight ratio
C.smaller propeller
D.larger power to weight ratio
