WPF，这个事件触发器该如何写

WPF，这个事件触发器该怎么写
<Button Padding="30" Content="熊俊">            
   <Button.Triggers>
      <EventTrigger RoutedEvent="Button.MouseEnter" >

         //这里该怎么写，使Content变为"张三"                    
      </EventTrigger>                   
   </Button.Triggers>
</Button>


问题：
一个事件触发器，当鼠标移到Button上时，使Content属性变为"张三"，普通的属性触发器就不用了，我指的是用事件触发器。
------解决方案--------------------
        <Button Name="huitest" Content="李四">
            <Button.Triggers>
            <EventTrigger RoutedEvent="Button.MouseEnter">
                    <BeginStoryboard>
                        <Storyboard>
                            <StringAnimationUsingKeyFrames Storyboard.TargetProperty="Content" >
                                <DiscreteStringKeyFrame Value="张三" KeyTime="0:0:0" />                               
                            </StringAnimationUsingKeyFrames>