轨道车制动部件三通阀校验周期是（）。
A、12个月
B、10个月
C、6个月
D、3个月
参考答案：C
________ is often the case with children, Tom was completely better by the doctor arrived.
[ ]
A. That
B. What
C. How
D. As
两个数______又叫做两个数的比．
