生石灰是由主要成分为( )的石灰石,在适当温度下煅烧出来的。
A.CaO
B.CaCO3
C.Ca(O2
D.CaSO4
参考答案:B
给饱和澄清石灰水加热.以下叙述不正确的是( )
A.溶液由澄清变浑浊
B.氢氧化钙的溶解度随温度的升高而增大
C.溶液仍为饱和溶液
D.溶液中溶质的质量分数减小
John opened the door. There () he had never seen before.
A. a girl did stand
B. a girl stood
C. did a girl stand
D. stood a girl