什么叫通风设施?
参考答案:
为保证风流沿着需要的方向和路线流动,在井下某些巷道中设置的一些用于控制风流、引导风流、割断风流的构筑物,这些构筑物就叫通风设施
—Jim,have you finished reading Harry Potter and Half-Blood Prince?
—No.I______ my father on the farm all day yesterday.
A.would help
B.had helped
C.was helping
D.have been helping
卖出开仓指的是投资者卖出认购期权或认沽期权