在采煤机运转（）年后，产煤100-300万吨后，机组应上井进行大修。
A.1-2
B.2-3
C.3-5
D.3-4
参考答案：B
-Good morning, Grand Hotel.
-Hello, I'd like to book a room for the nights of the 18th and 19th.
－ [ ]
A. What can I do for you?
B. Just a minute, please.
C. What's the matter?
D. At your service.
苔灰黑干燥主_________，苔灰黑润滑主_________。
