已知⑴ H2(g)+ 1/2O2(g)==H2O(g);△H1=aKJ•mol-1⑵ 2H2(g)+O2(g)==2H2O(g);△H2=bKJ•mol-1⑶ H2(g)+1/2O2(g)==H2O(l);△H3=cKJ•mol-1⑷ 2H2(g)+O2(g)==2H2O(l);△H4=dKJ•mol-1下列关系式中正确的是( )