A：过量的SO2通入NaOH溶液中：SO2+2OH-＝SO2-3+H2O
B：Fe（NO3）3溶液中加入过量的HI溶液；2Fe3++2I-=2Fe2++I2
C：NaNO2溶液中加入酸性KMnO4溶液：2MnO-4＋5NO-2＋6H+＝2Mn2++5NO-3+3H2O
D：NaHCO3溶液中加入过量的Ba(OH)2溶液：
已知一个样本含有30个数据，这些数据被分成4组，各组数据的个数之比为2：4：3：1，则第三小组的频数和频率分别为（ ）
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根据句意，写出括号内所给单词的适当形式。（1）“We don't want to be treated ____ (different) from others,” the disabled said.（2）When a strong wind came from the northwest, the heavy haze(雾霾) over Wuxi city began to____(appear).（3）It's lucky to have so much ____ (value) experience in learning English during the course.（4）I can't understand his ____ (silent) on such an important matter.
实验室里取8mL水并进行加热，下列需用的化学仪器组合正确的是①带铁夹的铁架台 ②10mL量筒 ③100mL量筒 ④酒精灯 ⑤石棉网 ⑥试管 ⑦试管夹 ⑧胶头滴管
