______千米的25%是80千米．
80÷25%=320（千米）．
答：320千米的25%是80千米．
故答案为：320．
---What do you think of the world-famous football player Messi from Argentina?
---I've never seen ______ one before. He was born to play football.
A．a creative
B．a most creative
C．the most creative
D．a more creative
已知A的阳离子有2个电子层，0.066 7 mol的A与足量的稀硫酸反应，放出2.24 L H2（标准状况下）；B的最高价氧化物中含氧量为60%，气态氢化物中含氢量为5.88%，B原子核内质子数和中子数相等。通过计算回答A、B各是什么元素？
