换偏旁变新字并组词。
沙---____、 ____ 砰---____、 ____
理---____ 、____ 槛---____、 ____
The article written by the famous economist is really _______. None of us can understand it.
下列代数式中整式有( )
1x,2x+y,13a2b,x-yπ,5y4x,0.5,a.