extjs4.0与extji3.0分别需要导入那些文件???    怎么有些类用不了，不能显示其效果？？

只要导resources/css/ext-all.css和ext-4.0.1/ext-all.js就行了吧

ExtJS3
<link href="script/extJs/extjs3/resources/css/ext-all.css" rel="stylesheet" type="text/css" />
<script src="script/extJs/extjs3/adapter/ext/ext-base.js" type="text/javascript"></script>
<script src="script/extJs/extjs3/ext-all.js" type="text/javascript"></script>

ExtJS4
<link href="script/extJs/extjs4/resources/css/ext-all.css" rel="stylesheet" type="text/css" />
<script src="script/extJs/extjs4/bootstrap.js" type="text/javascript"></script>