磨除塑料废边常用的磨具是（）
A.裂钻、球钻
B.氧化锌
C.布轮
D.石英粉
E.大砂轮
参考答案：E
下列离子方程式正确的是（ ）
A．锌和浓硫酸反应：Zn + 2H+ ="=" Zn2++ H2↑
B．氨水中加入氢氟酸：NH3·H2O + H+ ="=" NH4++ H2O
C．将过量SO2气体通入Ca(ClO)2溶液中：SO2 + Ca2++ 2ClO-+ H2O ="=" CaSO3↓ + 2HClO
D．硅石溶于烧碱溶液中：SiO2 + 2OH－="=" SiO32－+ H2O
—The classroom is clean it was yesterday.
—Sorry, I forgot to clean it.
A．as, as
B．so, as
C．not as, as
D．more, than
