挥发分随煤化程度的提高而下降。无烟煤的挥发分最低，通常小于10％。
参考答案：对
— Bad luck. They didn't offer the job to me.
— ______ You've been well prepared for the interview.
[ ]
A. So what?
B. What if?
C. How come?
D. What about?
无缝钢管的规格用（）来表示。
A.外径
B.内径
C.外径×内径
D.外径×壁厚
