克里斯泰勒认为，市场原则、交通原则和行政原则对城市等级和体系的形成起了综合作用。一般

Mail order is a term which describes the buying of goods or services by mail delivery（邮递）. The buyer places an order for the desired products with the salesman through some remote method such as through a telephone call or a website. Then, the products are delivered to the customer. The products are typically delivered directly to an address supplied by the customer, such as a home address, but sometimes the orders are delivered to a nearby retail location for the customer to pick up. Some businessmen also allow the goods to be shipped directly to a third customer, which is an effective way to send a gift to an out\|of\|town friend.
A mail order catalogue（目录）is a publication including a list of ordinary goods from a company. Companies who publish and operate mail order catalogues are treated as cataloguers within the industry. Goods are produced by people all over the world, such as in Australia, the USA, Canada, China etc. And now many cataloguers, just as with most retailers（零售商）, are increasingly buying goods from China.  

Title	Mail order
What	Mail order is a way of 小题1:by mail delivery.
How	People can place an order by 小题2:a telephone call or searching the website. People can choose the goods they want by 小题3:up in the catalogue.
Where	Now goods made in 小题4:are more and more popular in foreign countries.