．It is said that the novel Henry had dev

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问题选择题

．It is said that the novel Henry had devoted so many years to ______published last week.

A．get

B．gets

C．got

D．getting

答案

答案：C

单项选择题

次氯酸钠使用浓度是

A．1%
B．2%
C．0.5%
D．1:32
E．1:213

填空题

NaCl溶液中混有CaCl₂、Na₂SO₄等杂质，为了获得NaCl溶液，在溶液中依次加入过量的BaCl₂溶液、Na₂CO₃溶液，过滤，再向滤液中加入适量盐酸。实验中加入过量的BaCl₂溶液是为了除去；加入过量的Na₂CO₃溶液的目的是。