如何使用select的某些option不能选?
例如: 
  <select   name= "test ">  
  <option   value= "a "> a </option>  
  <option   value= "b "> b </option>  
  <option   value= "c "> c </option>  
  </select>  
 我在select中显示a,b,c三个选项,但其中b是无法选中的? 
------解决方案-------------------- <select name= "test ">  
  <optgroup label= "group1 " />  
  <option> a </option>  
  <option> b </option>  
  <optgroup label= "group2 " />  
  <option> c </option>  
  <option> d </option>  
  </select>
------解决方案--------------------http://topic.csdn.net/t/20060324/13/4637350.html