A:Ca(OH)2 →Cl2 Ca(ClO)2 →SO2 HClO
B:Fe →高温H2O Fe2O3 →盐酸 FeCl3
C:SO2 →NH3⋅H2O NH4HSO3 ⇌SO2⋅H2ONH3⋅H2O (NH4)2SO3
D:FeS2 →煅烧O2 SO3 →H2O H2SO4
— They are Mary's bag. She left it on the playground just now, but now she can't find it.
告诉别人你是一个叙述者,应该说:I'm the narrator.