受水害威胁的煤矿，在煤层露头风化带必须留设防隔水煤（岩）柱。
参考答案：对
The shop ______ at 7: 00 a.m. and it ______ for twelve hours every day.[ ]
A. opens; is open
B. is opened; opens
C. is open; has opened
D. opened; opens
治疗创伤性溃疡首先选用的是（）
A.抗生素药膜局部贴敷
B.去除局部刺激因素
C.确炎舒松局部注射
D.达克罗宁局部涂布
E.中药粉外敷
