变换图片问题

<html><head><title>新建网页 1</title>
</head><body><p><img border="0" src="Female.gif" width="23" height="21" id="im1">
<a href="javascript:void(0)" onclick="im1.src='on.gif';"im2.src='Male.gif'">ggggggggggggggggggggggggggggggggggggggggggggggggg</a></p><p><img border="0" src="Male.gif" width="23" height="21" id="im2">
<a href="jsvascript:void(0)"  onclick="im2.src='on.gif';im1.src='Female.gif'">mmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm</a></p></body></html>