Merge remote-tracking branch 'origin/master'

application/api/controller/Production.php

@@ -2612,12 +2612,12 @@ class Production extends Base
         // 处理上标
         if (isset($style['vertAlign']) && $style['vertAlign'] === 'superscript') {
             // LaTeX上标需要考虑嵌套，用{}包裹内容
-            $content = "$^{{$content}}$";
+            $content = '$^{{'.$content.'}}$';
         }
 
         // 处理下标
         if (isset($style['vertAlign']) && $style['vertAlign'] === 'subscript') {
-            $content = "$_{{$content}}$";
+            $content = '$_{{'.$content.'}}$';
         }
 
         return $content;