下列物质敞口放置一段时间，变质且质量增加的是（ ）
A．浓盐酸
B．浓硫酸
C．烧碱
D．大理石
答案：C
引起上牙弓狭窄，腭盖高拱是（）
A.伸舌吞咽
B.口呼吸
C.偏侧咀嚼
D.咬下唇习惯
E.咬上唇习惯
The pollution question as well as several other issues is going to be discussed when the Congress is in ______ again next spring.
A. assembly B. conference C. convention D. session
