A:①②
B:②③
C:①③
D:①④
C(s)+O2(g)═CO2(g)△H=﹣393.5kJ/mol
则:2Fe(s)+ 32 O2(g)═Fe2O3(s)的△H是( )
When you see an English film or talk with native speakers, observe their facial expressions and g____.