A:用2B铅笔芯做导电性实验
B:用过滤的方法把硬水变成软水
C:用冷碟子放在蜡烛火焰上方制取炭黑
D:用食醋除去热水瓶胆内的水垢
根据遗传图解回答下列问题.
句子改错
He came into the classroom and the students stopped to talk.
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