水冷壁受热面无论是积灰结渣或积垢,都会使炉膛出口烟温()
A、不变
B、增高
C、降低
D、突然降低
参考答案:B
打磨工具配有不同的打磨垫,研磨中途底漆一般采用()。
A.硬磨垫
B.软磨垫
C.超软磨垫
D.耐高温磨垫
—Must I come at four o'clock?
—Oh, no, you ______. [ ]
A. don't
B. mustn't
C. don't have to
D. can't