Aggregate 聚合用法
var listb= ListA.Where(x => x.Id.Equals(obj.Id)).Select(x => x.SubData).Aggregate((x, y) => x.Concat(y).Distinct().ToList()).ToList();
var listb= ListA.Where(x => x.Id.Equals(obj.Id)).Select(x => x.SubData).Aggregate((x, y) => x.Concat(y).Distinct().ToList()).ToList();