液压传动的断路器交流电动油泵的熔断器的熔丝额定电流应比电动机的额定电流大（）倍
A.1.2
B.1.5
C.2～3
D.5～7
参考答案：C
—I was late for work this morning.
—_________. You started early, didn't you?[ ]
A. Why not?
B. So what?
C. How come?
D. Never mind.
套管换热器的主要优点是什么？
