问题
选择题
—I'm too nervous to speak in front of so many people.
—_____,John. You can do it. [ ]
A. I hope so
B. You're right
C. Don't worry
D. Congratulations
答案
答案：C
搜题请搜索小程序“爱下问搜题”
—I'm too nervous to speak in front of so many people.
—_____,John. You can do it. [ ]
A. I hope so
B. You're right
C. Don't worry
D. Congratulations
答案：C
＋2e－＝PbSO4＋2H2O，则在a电极上发生的反应可表示为_________________。若电池工作一段时间后，a极消耗0.05 mol Pb，则W的浓度由质量分数39 % (密度1.3 g / cm3)变为______mol /L。