有关行车人员必须执行（），服从调度指挥。
参考答案：调度命令
You must be very tired. Why not ___________a rest?
A．to stop to have
B．to stop having
C．stop to have
D．stop having
什么是蒸汽品质？影响蒸汽品质的因素有哪些？
