【题目】下列代码创建一个新线程并启动线程。
Runnable target=new MyRunnable();  
Thread myThread=new Thread(target);  
其中，（    ）类可以创建target对象，并能编译正确。

public class MyRunnable extends Runnable { public void run(){} }

public class MyRunnable extends Object { public void run() {} } 

 public class MyRunnable implements Runnable {public void run() {}}

public class MyRunnable extends Runnable {void run() {}}