为何在慕课的测试环境里没有键盘和鼠标事件两个阴影的bug，但是换到本地环境就又不行了？
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<cite>请选择分类</cite>
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<li id="li"><a href="javascript:;" selectid="1">ASP开发</a></li>
<li><a href="javascript:;" selectid="2">.NET开发</a></li>
<li><a href="javascript:;" selectid="3">PHP开发</a></li>
<li><a href="javascript:;" selectid="4">Javascript开发</a></li>
<li><a href="javascript:;" selectid="5">Java特效</a></li>
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