1.abstractclassColor2{2.//insertcodehere3.}4.5.publicclassBlue2extendsColor2{6.publicStringgetRGB(){return"blue";}7.}和4个声明:publicabstractStringgetRGB();abstractStringgetRGB();privateabstractStringgetRGB();protectedabstractStringgetRGB();分别插入到第2行,有多少行可以编译?()
A、0
B、1
C、2
D、3
现有:1.abstractclassColor2{2.//insertcodehere3.}4.5.publicclassBlue2extendsColor2{6.public