大断面竖井施工工艺有哪几步?
参考答案:
⑴凿岩
⑵提升工作盘
⑶装药、联线、爆破
⑷通风、清除炮烟
⑸下落工作盘
⑹出岩
⑺临时支护和永久支护
⑻下放凿岩设备
⑼再次凿岩
In order to stop his wife from attending the party, he took away the key to their car _____.
A.by mistake
B.in surprise
C.on purpose
D.by chance
在SQL中,通过使用视图,能够使在关系规范化时被分解的关系()连接起来,能够增强数据库的()性。