运行时间超过15年、寿命超过设计使用寿命的转子、低压焊接转子、承担调峰起停频繁的转子，应适当缩短检查周期。
参考答案：对
—The supermarket _____ at 9 a.m. and it is _____ at 9 p.m. every day.
—So I have to go there before 9 p.m.[ ]
A. open; close
B. opens; closed
C. opens; closes
D. open; closed
下列有关热力环流的图示，不正确的是（）
A.A
B.B
C.C
D.D
