C# List<T> 对于某个字段去重复
gradeSubjectItem.teacher = teacherInfos.Where((x, i) => teacherInfos.FindIndex(z => z.guid == x.guid) == i).ToList();
gradeSubjectItem.teacher = teacherInfos.Where((x, i) => teacherInfos.FindIndex(z => z.guid == x.guid) == i).ToList();