有过热器的锅炉,应用蒸汽吹洗过热器。吹洗时,锅炉压力应保持在工作压力的75%左右,吹洗时间不得少于______min。
A.5
B.8
C.10
D.15
参考答案:D
吸附界面有()、()、()和()。
--- Do you play a musical _____?
--- Yes, I do. I started playing the piano when I was four.
A.engineer
B.gift
C.instrument
D.football