fix bug

apps/exams/_static/js/public_exam_3g.js

@@ -60,9 +60,7 @@ $(function() {
 
 
         if (limit > 0 && question_num >= limit) {
         if (limit > 0 && question_num >= limit) {
             let page = $("#ex" + question_num + ' .next');
             let page = $("#ex" + question_num + ' .next');
-            page.unbind('click', function () {
-
-            })
+            page.unbind('click');
             page.attr({'style': 'background:rgba(245,166,35,1);'});
             page.attr({'style': 'background:rgba(245,166,35,1);'});
             page.text('去支付');
             page.text('去支付');
         }
         }