js怎样实现下拉框改变，它旁边的图像也改变_图象特效

<select id="s1" onchange='document.getElementById("pic").src=this.value'> <option value="/upload/20080918164946929.gif">biggrin</option> <option value="/upload/20080918164946913.gif">confused</option> <option value="/upload/20080918164946995.gif">cool</option> <option value="/upload/20080918164946667.gif">eek</option> <option value="/upload/20080918164946725.gif">frown</option> <option value="/upload/20080918164946792.gif">han</option> <option value="/upload/20080918164946356.gif">mad</option> <option value="/upload/20080918164946762.gif">redface</option> <option value="/upload/20080918164946633.gif">rolleyes</option> <option value="/upload/20080918164946854.gif">smile</option> <option value="/upload/20080918164947307.gif">tongue</option> <option value="/upload/20080918164947238.gif">wink</option> </select> <img id="pic" src="http://files.jb51.net/upload/20080918164946929.gif" border="0" style="max-width:90%" alt="js怎样实现下拉框改变，它旁边的图像也改变_图象特效" >
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