以下哪条命令可以清楚客户端DNS查询缓存（）

A.ipconfig/all

B.ipconfig/

C.Ipconfig/displaydns

D.Ipconfig/flushdns

请在下面代码中加入监听器语句 【15】 。 import java.awt.*; import java.applet.Applet; public class Simple extends Applet implements MouseListener { StringBuffer; Public void init() {______//加监听器语句buffer=new StringBuffer();addItem("initializing....."); } Public void moseEntered(MouseEvent event) {} Public void moseExited(MouseEvent event) {} Public void mosePressed(MouseEvent event) {} Public void moseReleased(MouseEvent event) {} Public void moseClicked(MouseEvent event) { addItem("click!..."); } }