已知单项式3xa+1y4与﹣2yb﹣2x3是同类项,则下列单项式,与它们属于同类项的是( )
A:﹣5xb﹣3y4
B:3xby4
C:xay4
D:﹣xayb+1
When are they going to meet each other?
生产某阻燃剂(Sb2O5)的化学方程式为X+2H2O2═Sb2O5+2H2O,推断X的化学式为( )
读北京图回答: