给定程序的输出是什么？(     )

import java.util.Properties; 
public class Test72 { 
    public static void main(String[] args) { 
        Properties p = new Properties(); 
        p.put("grade", "master"); 
        Properties p2 = new Properties(p); 
       System.out.println(p2.get("grade") + " : " + p2.getProperty("grade")); 
    } 
}