电梯井的井壁除开设电梯门洞和通气孔洞外,不应开设其它洞口。电梯门可采用栅栏门。()
参考答案:错
The price of the houses in this district_________from 5% to 7% in the past two months.
A.has fallen
B.has been fallen
C.was fallen
D.was falling
气瓶操作中,氧气与乙炔瓶的距离为多远?