肺泡中的氧气进入肺泡周围毛细血管的血液中,至少通过的细胞层数是[ ]
A.1层
B.2层
C.3层
D.4层
答案:B
Had I run out of gas, I ought to have called the garage.
A.had
B.would have
C.would
D.should have
带电作业工作负责人在带电作业工作开始前,应与调度值班员()。需要停用重合闸的作业,应由调度值班员履行()手续。带电作业结束后应及时向调度值班员汇报。
A.联系
B.申请
C.许可
D.批准