fix bug

apps/classroom/Tpl/default/Index/theme_x7_w3g.html

@@ -113,7 +113,7 @@
                     开始做题
                     <!-- 下载预览提示 -->
                     <!-- <div v-show="yulan==index"> -->
-                    	<div class="yulanBox" v-if="false">
+                    	<div class="yulanBox" v-if="true">
                         <div class="tips_box">
                           <img class="close_yulan" src="/addons/theme/stv1/_static/img/guanbi@2x.png">
                         	<div class="tips_title">提示</div>