若有以下程序 interface Father{ // ① double f =3.5; public void show(){} //② } class Son implements Father{ public void show(){ f = 5.0; //③ } } class Main{ public static void main(String []s){ Father f = new Father(); //④ }} 则下面描述错误的是( ) A.
①句无语法错误 B.
②句有语法错误 C.
③句无语法错误 D.
④句有语法错误