如下图所示,相等质量的铁和锌与足量的稀H2SO4充分反应,产生氢气的质量(m)与反应时间(t)的正确关系是( )
A:
B:
C:
D:
— ______ people travel every year?
— Perhaps when we are talking about it, more than 100 planes have taken off around the world.