The __________ is yellow. [ ]
A. teacher desk
B. teachers' desks
C. teacher's desk
答案:C
两瓶驱蚊水一共500毫升,大瓶用去40%,小瓶用去10%,两瓶中剩下的驱蚊水一样多.小瓶中原有驱蚊水多少毫升?(用两种方法解)
下列两种气体的分子数一定相等的是( )
A.质量相等、密度不等的O2和CO
B.等体积等密度的CO和N2
C.等温等体积的O2和N2
D.等压等体积的N2和CO2