can supermarkets serve the public interest? First of all, large supermarket chains can provide a large number of product options to the public. To begin with, there are quantities of products in supermarkets since thousands of farmers and suppliers offer products to a small number of supermarkets. For example, in United Kingdom, each of the four supermarkets needs 7000 suppliers, which ensures a variety of products (Young, 2012). More specifically, statistics on supermarket chains from around world support that on average, every supermarket stores 47000 items (Consumer Reports Magazine, 2014). In addition, according to Berger, Draganska and Simonson (2007), the diversity of brands in supermarkets also offers plenty of options to customers. Thus, numerous products and varieties of brands make it possible for customers to have many choices. Nevertheless, some critics argue that there are too many products which make customers feel confused and waste time to make a choice. Studies show that the average American spends more than half an hour per day shopping in supermarkets (Goodman, 2008). That is, many customers spend long time on shopping in supermarkets because of too many choices. Furthermore, according to Schwartz (2006), some customers will be under pressure and feel dissatisfied when they face so many product options in supermarkets. It may be true that choice overload exists in supermarkets and this will make some consumers feel anxious. However, most customers still require a wide range of products to choose. That means more products in supermarkets are better for most customers (Rana, Osman and Islam,2014). Therefore, it is clear that large supermarket chains serve the public interest because they provide a great many products to the public.

Is this sentence OK? Large supermarket chains are able to serve public interest because they provide large choice of products and most products in supermarkets are cheap.

Student should not use mobile phones in class2 Students would rely too much on their mobile phones if they use their phones in class. First of all, once students use mobile phones frequently, they may not want to solve learning problems by themselves but they would just check for answer online.A study shows that smartphone users who are intuitive thinkers prefer to depend on their device’s search engine instead of their own brainpower(University of Waterloo,2015) .In this way smartphones make them become lazier in a long-term. Also,students would cheat in test with their smart phones .According to Common Sense Media(2009),more than 35% teenagers admit to cheating with their cell phones ,and many students do not think their actions are cheating. In other words ,those students get use to checking information online to solve problems so that they take it for granted that they can use smart devices in test.In short,students would depend too much on their phones in class.

Student should not use mobile phones in class Students can not concentrate on learning if they use mobile phones in class . Firstly , They could focus on social media rather than text book.According to Matchan(2015), students prefer using digital devices for texting,tweeting and video chatting during the lecture.If students are allowed to use smart phones during the class ,they may check the feed on the social media instead of studying. Secondly ,students may be distracted by games on the mobile phones . Nowadays , there are more and more interesting games on smart phones such as Pokemon Go , Driving School and so on .However, students are too young to control themselves . In South Australia ,children spend 67% of time playing online games when they on the Internet at home.(1345.4 - SA Stats, 2010) .So we can speculate that students would also spend much time on mobile phone games if they bring smart phones to class. Thus, it is clear that students should not use mobile phones in class because they would not focus on studying if they use electronic devices.