在传统式盈亏临界图中，可以用横轴表示销售收入量，用纵轴表示成本，纵轴与横轴的金额最好保持一致，此时总成本线的仰角应大于45°。
参考答案：错
氧气管道通过烟道、通行地沟应加上适当的防护。( )
—How did you play in the match —Well, our team was ahead by 2 to zero during the first half, but we ______ in the last ten minutes.
A．had lost
B．have lost
C．were losing
D．lost
