用css控制select的宽度:(最短100,如果有宽度超过100的选项,将select的宽度调整为最长选项的宽度)<br/>
<select style="width:expression((this.offsetWidth>100)?'auto':'100')">
<option >hellohellohellohellohellohellohellohellohellohello</option></select><br/>
<select style="width:expression((this.offsetWidth>100)?'auto':'100')">
<option ></option></select><br/>