Jim often ____ ____ ____ a prince when he is at a party.
已知一组数据1,4,5,2,3,则这组数据的平均数是( )
①CH3Cl、②CH2C12、③CHCl3、④CCl4.
与北方比较,南方地区( )
下列关于黄河与长江的说法正确的是( )