外伤性血气胸最简单可靠的诊断依据是( )
A.呼吸困难,发绀 B.气管移位C.胸部X线检查见有气液平面 D.胸穿抽出不凝固血液和气体
参考答案:D
— Tom’s never done extra work for his class, _______he?
—_______. He is the laziest boy in his class.
A.has; Yes
B.is; No
C.is; Yes
D.has; No
煤的挥发分越多,则其发热量越高。