fix bug

apps/exams/_static/js/public_exam_3g.js

@@ -58,6 +58,10 @@ $(function() {
             var question_num = parseInt($(this).data("question_num")) + 1;
             var question_num = parseInt($(this).data("question_num")) + 1;
         }
         }
 
 
+        if (limit > 0 && question_num > limit) {
+            $(this).text('去支付');
+        }
+
         console.log(limit, question_num);
         console.log(limit, question_num);