Fatal error: Uncaught Error: Class 'Think\Model' not found in C:\Project\WWW\SanGuo130\ThinkPHP\Library\Think\Model\MergeModel.class.php:16 Stack trace: #0 {main} thrown in C:\Project\WWW\SanGuo130\ThinkPHP\Library\Think\Model\MergeModel.class.php on line 16