井筒工作面预注浆应该设置（），其目的是为了防止冒水跑浆。
A.保护盘
B.混凝土止水垫
C.保护岩柱
D.保留岩帽
E.止浆盘
参考答案：B, D
After years of war, the people in that country were eager to live in_________.
A．peace
B．public
C．silence
D．trouble
