某商店经营儿童益智玩具，已知成批购进时的单价是20元.调查发现：销售单价是30元时，月销售量是230件，而销售单价每上涨1元，月销售量就减少10件，但每件玩具售价不能高于40元. 设每件玩具的销售单价上涨了x元时（x为正整数），月销售利润为y元.

（1）求y与x的函数关系式并直接写出自变量x的取值范围；

（2）每件玩具的售价定为多少元时，月销售利润恰为2520元？

（3）每件玩具的售价定为多少元时可使月销售利润最大？最大的月利润是多少？

Logistics System A logistics system consists of different functions and activities,such as the following: 1.Customer service is a core function in the logistics process.Each business entity should have a customer service department to handle complaints,special orders,loss and damage claims,returns,bills problem,and etc．This function becomes crucial because any dissatisfaction can lead to failure to retain customers. 2.Inventory management is to maintain the stock of raw materials and half-finished products.In order to satisfy the customers＇demand and minimize costs,a company should establish an optimal level of inventory to meet the market demand that exceeds our expecta-tions,and at the same time,minimize your inventory holding costs and inventory write-down costs. 3.Transportation has taken a great role in many logistics systems for two reasons.First of all,globalization and importing-exporting activities make most products necessary to be transferred from one country to another.Secondly,information revolution has propelled the manufacturing process and consumer behaviors to be changed drastically.Traditional trans-portation methods need to be upgraded to accommodate modern transportation demand,therefore,containerization and usage of information sharing system emerge. 4.Storage is needed to manage the materials and store ready-for-market products in warehouses.There is new technology applied in the storage,for example,automatic ware-house.Old-fashioned warehouse has become the distribution center where container trucks deliver and pick up the goods. 5.Information system links all logistics processes and integrates all information to en-sure all the handling of large quantity of goods are delivered in an efficient,cost-effective and accurate manner. Questions:

Why is transportation so important to the current business environment？（）

A.Transportation means are limited．

B.Because of globalization,exports and imports activities.

C.Transportation is costly.

D.Because of time.