<html><head><script>function lighton() { document.getElementById('myimage').src = "/i/eg_bulbon.gif";}function lightoff() { document.getElementById('myimage').src = "/i/eg_bulboff.gif";}</script></head><body><img id="myimage" onmousedown="lighton()" onmouseup="lightoff()" src="/i/eg_bulboff.gif" /><p>点击鼠标并按住！</p></body></html>