完全燃烧体积为6m3的天然气,放出的热量为_________J 。(天然气的热值为7.5×107J/m3)
4.5×108
Jim and Kate _____ English.[ ]
A. are good in
B. are good at
C. is good at
D. are good with
常采用()作为印制高档包装盒、袋的纸。
A、牛皮地白板纸
B、胶版纸
C、涂布白卡纸
D、白地白板纸