A:see off him
B:see him off
C:pick him up
D:pick up him
等高线的疏密状况表示坡度的____:坡度陡的地方,等高线密集;坡度缓的地方,等高线稀疏。等高线重叠处是____。
2ZnS(s)+3O2(g)═2ZnO(s)+2SO2(g)△H1=﹣930kJ•mol﹣1
2C(s)+O2(g)═2CO(g)△H2=﹣221kJ•mol﹣1
ZnO(s)+CO(g)═Zn(g)+CO2(g)△H3=198kJ•mol﹣1
选出你所听到的单词( )