离心泵的小修周期是3-4个月，大修周期是（）。
A.8-10个月
B.5-7个月
C.12-18个月
参考答案：C
— Can you tell me something about _________ science.
— OK. _ Nobel Prize in Chemistry is usually awarded to Americans.
A．the; The
B．/; The
C．a; /
D．the; /
《音乐的体制》
