A:②④
B:①③
C:①④
D:②③
⑴____hair hear
⑵____there where
⑶____chair here
⑷____pear bear
A
B
C
D
方案
NaHCO3:9.6 g
Na2CO3:21.8 g
将NO2球浸泡在冷水和热水中
目的
探究浓度对化学反应速率的影响
制备氨气
室温下比较NaHCO3和Na2CO3的溶解度
探究温度对化学平衡的影响
The students carried their books away from the school ____ ____ .