Standing on top of the building, ______.

A．the whole city could be seen

B．nothing could be seen

C．we could see the whole city

D．all could be seen

设N_A为阿伏伽德罗常数的值。下列叙述正确的是

A．1mol甲醇中含有C-H键的数目为4N_A

B．25℃,PH=13的NaOH溶液中含有OH^-的数目为0.1N_A

C．标准状况下，2.24L已烷含有分子的数目为0.1N_A

D．常温常压下，Na₂O₂与足量H₂O反应,共生成0.2molO₂,转移电子的数目为0.4 N_A