13. When shopping, after-sale service should be considered as an important factor.
购物时，售后服务是一个重要因素。
还能这样说：
After-sale service is an important consideration when go shopping.
After-sale service takes up an important position when do some shopping.
14. After-sale service costs little money.
售后服务价格不高。
还能这样说：
It takes little money to serve after the transaction.
One can pay little money for the after-sale service.
15. After-sale service is a kind of marketing strategy.
售后服务是一种营销策略。
还能这样说：
One of the marketing tactics is back-up service.
After-sale service is a strategy to promote the goods.
16. I want to know something about after-sale service.
我想了解一些售后服务的信息。
还能这样说：
I'd like to inquire some information about the after-sale service?
I want to learn some information about after-sale service.
17. Your car can be serviced regularly.
你的车可以定期做保养维修。
还能这样说：
Your car can enjoy the after-sale service at a regular time.
We can service your car regularly.