假设你是李明，你有一个外国朋友---戴维。请给他写封信给他介绍一个中国传统节日。120-180词

Qingming Festival,i return home to worship my grandfather.Qingming Festival is a folk Festival.In the past,In the past,the Qingming Festival was called "Arbor Day".But Today,Chinese visit their family graves to tend to any underbrush that has grown.Weeds are pulled,and dirt swept away,and the family will set out offerings of food and spirit money.Unlike the sacrifices at a family's home altar,the offerings at the tomb usually consist of dry,bland food.One theory is that since any number of ghosts rome around a grave area,the less appealing food will be consumed by the ancestors,and not be plundered by strangers.