There ______ a number of people in the airport. The number of people who travel by plane ______ larger

than before. [ ]

A．are, are

B．are, is

C．is, is

D．is, are

氢氧燃料电池可以使用在航天飞机上，其反应原理示意图如右下图。下列有关该氢氧燃料电池的说法错误的是

A．该电池工作时将化学能转化为电能

B．电流从电极b经外电路流向电极a

C．该电池中的电极b是正极

D．在电极a上发生还原反应