井下可使用灯泡、电炉取暖和加热物品。（）
参考答案：对
已知等差数列{an}中，a1+a2+…+a9=81．则a5=______．
As many as 150 miners died in the accident．If only the mine - owners ____ enough attention to the safety measures!
A．paid
B．should pay
C．would pay
D．had paid
