有两个集合，删除一个集合中包含的另一个集合的数据，如何使用扩展方法删除？

Question

//使用扩展方法删除集合companies中的allcompanys的数据

 var allcompanys = companies.Where(x =>
                   nations.Where(z => z.OnArea == "Asia").
                   Any(z => cities.Where(o => o.OnNation == z.Chinese).Any(o => o.Chinese == x.OnCity))).ToList();
                companies.ForEach(x=> { allcompanys.Contains(x); }) ;

//这里已经找到了两个集合companies和allcompanys，想定义一个扩展方法RemoveList来直接删除，成为这样的companies.RemoveList(allcompanys);

Answer 1

companies = companies.Except(companies.Where(x =>
                   nations.Where(z => z.OnArea == "Asia").
                   Any(z => cities.Where(o => o.OnNation == z.Chinese).Any(o => o.Chinese == x.OnCity))).ToList()).ToList();

或者

var allcompanys = companies.Where(x =>
                   nations.Where(z => z.OnArea == "Asia").
                   Any(z => cities.Where(o => o.OnNation == z.Chinese).Any(o => o.Chinese == x.OnCity))).ToList();
                allcompanys.ForEach(x=>{ companies.Remove(x); }) ;