事故隐患分为（）隐患两种。
参考答案：一般事故隐患和重大事故
—Are these his cousins?
—__________. They are his brothers.
A．Yes, they are.
B．No, these aren’t.
C．Yes, these are.
D．No, they aren’t.
在普通气候环境中配制普通水泥混凝土应优先选用( )。
A．硅酸盐水泥
B．普通水泥
C．矿渣水泥
D．粉煤灰水泥
