①将铜片接在电池的正极上,
②将银片接在电源的正极上,
③在铜片上发生的反应是:Ag++e﹣═Ag,
④在银片上发生的反应是:4OH﹣﹣4e﹣═O2+2H2O,
⑤需用CuSO4溶液,
⑥需用AgNO3溶液作电解液.
A:②③⑥
B:①③⑥
C:①④⑤
D:②③④⑥
北方地区是指中国东部____以北的地区,面积约占全国的20%,人口约占全国的40%。
A good listener takes part in the conversation, ______ ideas and raising questions to keep the talk flowing.
设集合A=x|x-1x+1<0,B=x|x-1<a,则“a=1”是“A∩B=∅”的( )
Either Eve or Herb ___________ been invited by Lucy's parents already.