停电工单填写了复电信息以后（）
A、停电申请信息可以删除
B、停电申请信息不能删除，只能作废删除工单
参考答案：B
— Why is the classroom so dirty?
— Sorry, sir. It yesterday. We forgot to do it. [ ]
A．doesn't clean
B．didn't clean
C．isn't cleaned
D．wasn't cleaned
安装时具有方向性，不得装反的是（）。
A.闸阀
B.截止阀
C.旋塞阀
D.球阀
E.止回阀
