<script>

    window.onload = function (ev) {

        // 调用对象前先创建

        // 2

        var vcar=new Car("奔驰","E2000",50,2);

        // 3

        vcar.startup();

        vcar.Startengine();

        vcar.changeSpeed();

        vcar.swerve();

        vcar.stop();

        vcar.Turnofftheengine();

    }

//1

    function Car(make, model, currentSpeed, displacement) {

       // this.make = "奔驰";

       // this.model = E2000;

       var currentSpeed = currentSpeed;

      //  this.displacement = 2;

        //启动引擎

        this.Startengine = function () {

            var speed =currentSpeed;

            document.write("<br>"+"启动引擎:"+speed);

        };

        //启动

        this.startup = function () {

            document.write("启动:0");

        };

        //加速

        this.changeSpeed = function () {

            var speed =currentSpeed*2;

            document.write("<br>"+"加速:"+speed);

            ///return speed;

        };

      // car.changeSpeed();

        //转向

        this.swerve = function () {

            var speed =currentSpeed/5*2;

            document.write("<br>"+"转向:"+speed);

        };

        //刹车

        this.stop = function () {

            var speed =0;

            document.write("<br>"+"刹车:"+speed);

        };

        //关闭引擎

        this.Turnofftheengine = function f() {

            var speed =currentSpeed/5/2;

            document.write("<br>"+"关引擎:"+speed);

        };

    }

</script>