修改了一个display参数，Django不能启动，报错为：
django.core.management.base.SystemCheckError: SystemCheckError: System check identified some issues:
ERRORS:
<class 'myApp.admin.GradesAdmin'>: (admin.E108) The value of 'list_display[3]' refers to 'ggirlbum', which is not a callable, an attribute of 'GradesAdmin', or an
attribute or method on 'myApp.Grades'.
翻译一下：
“list_display[3]”的值是指“ggirlbum”，它不是可调用的、“GradesAdmin”属性或
“myApp.Grades”上的属性或方法。
然后我就找到错误了，全是自己手抖写错了ggirlbum：
list_display = ['pk', 'gname', 'gdate', 'ggirlbum', 'gboynum', 'isDelete']
改成↓↓↓↓↓↓↓↓↓↓↓↓↓
list_display = ['pk', 'gname', 'gdate', 'ggirlnum', 'gboynum', 'isDelete']