问函数没有定义，没有明显的原因。

EN

package  {

import flash.display.MovieClip;
import flash.events.MouseEvent;
import flash.events.KeyboardEvent;
import flash.events.Event;
import flash.ui.Keyboard;


public class Code extends MovieClip {

    var charSpeed:int = 0;
    var velocity:int = 0;
    var gravity:Number = 1;
    var Jump:Boolean = false;


    public function startGame(){
         stage.addEventListener(KeyboardEvent.KEY_DOWN, checkKeyDown);
         stage.addEventListener(KeyboardEvent.KEY_UP, checkKeyUp);
     }

    public function Code() {
        // constructor code
    }

    function checkKeyDown(evt:KeyboardEvent){
        if (evt.keyCode == Keyboard.LEFT){
            charSpeed -= 10;
        }
        if (evt.keyCode == Keyboard.RIGHT){
            charSpeed += 10;
        }
        if (evt.keyCode == Keyboard.DOWN){
            if(!Jump){
                velocity -= 14;
                Jump = true;
            }
        }

    function checkKeyUp(e:KeyboardEvent){
        if (e.keyCode == Keyboard.LEFT){
            charSpeed = 0;
        }
        if (e.keyCode == Keyboard.RIGHT){
            charSpeed = 0;
        }
    }