区域调度机构应当在当月()个工作日编写本网《调度运行指标月报》。
A.10
B.8
C.5
D.7
参考答案:A
简述JT-C机车信号双机热备原理。
-Sir,may I borrow some new books?
-Sorry,you can't________you haven't turn back those you borrowed one month ago.
A.unless
B.before
C.because
D.until