51help TIY
码：
<html> <head> <script type="text/javascript"> function selectMultiple() { document.getElementById("mySelect").multiple=true } </script> </head> <body> <form> <select id="mySelect" size="4"> <option>苹果</option> <option>桃子</option> <option>香蕉</option> <option>桔子</option> </select> <input type="button" onclick="selectMultiple()" value="选择多个"> </form> <p>在您点击 ” ” 。</p> </body> </html>
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