二次热分解后产生的气体从炭化室顶部空间经上升排出，这些气态产物称为( )。
A．水蒸气 B．干煤气 C．游离碳 D．粗煤气
参考答案：D
A．B超成像
B．声呐测距
C．一种速度测定器
D．分贝仪
The story that happened 30 years ago still remains _____ in my mind as if it _____ yesterday. [ ]
A. clean; happened
B. fresh; happened
C. clear; was happened
D. clearly; happened
clean; happened