单项选择题 Given a class Repetition： 1.package utils； 2. 3.public class Repetition{ 4.public static String twice（Strings）{returns+s；} 5.} and given another class Demo： 1.//insert code here2. 3.public class Demo{ 4.public static void main（String[]args）{ 5.System.out.println（twice（"pizza"））； 6.} 7.} Which code should be inserted at line 1 of Demo.java to compile and run Demo to print“pizzapizza”？（）

单项选择题 Given classes defined in two different files： 1.package util； 2.public class BitUtils{ 3.private static void process（byte[]b）{} 4.} 1.package app； 2.public class SomeApp{ 3.public static void main（String[]args）{ 4.byte[]bytes=newbyte[256]； 5.//insert code here 6.} 7.} What is required at line 5 in class SomeApp to use the process method of BitUtils？（）

多项选择题 GivenafileGrizzlyBear.java： 1.package animals.mammals； 2. 3.public class GrizzlyBear extends Bear{ 4.voidhunt（）{ 5.Salmons=findSalmon（）； 6.s.consume（）； 7.} 8.} and another file，Salmon.java： 1.packageanimals.fish； 2. 3.public class Salmon extends Fish{ 4.voidconsume（）{/*dostuff*/} 5.} Assume both classes are defined in the correct directories for theft packages，and that the Mammal class correctly defines the findSalmon（）method.Which two changes allow this code to compile correctly？（）