A:用FeCl3溶液腐蚀印刷电路板:Fe3++Cu=Fe2++Cu2+
B:Na放入水中,产生气体:Na+H2O=Na++OH﹣+H2↑
C:向FeCl3溶液中滴加淀粉碘化钾溶液,溶液变蓝:2Fe3++2I﹣=2Fe2++I2
D:NaHCO3溶液与NaOH溶液反应:OH﹣+HCO3﹣=CO2↑+H2O
下列句子中标点符号的使用,正确的一句是( )
如图:已知在△ABC中,AB=AC,D为BC边的中点,过点D作DE⊥AB,DF⊥AC,垂足分别为E,F.求证:△BED≌△CFD.
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.