比如说我们要从用户表customer和用户订单表orders中，查询上海的用户，在最近10个月中至少消费3笔满10快钱的用户的姓名和年龄
var results = from customer in customers
              where customer.State == "WA"
              let custOrders = (from order in orders
                                where customer.ID == order.ID
                                select new { order.Date, order.Amount })
              where custOrders.Count(co => co.Amount >= 10 &&
                                     co.Date >= DateTime.Now.AddMonths(−10)) >= 3
              select new { customer.Name, customer.Age };
foreach (var result in results) {
Console.WriteLine("{0} {1}", result.Name, result.Age);
}

就是XXX.XXX().XXX() 这种方式。