题目

Nowadays Dianzan is one of the most popular words on the Internet When you think someone's articles are _____， or when you are moved by what someone writes, you can click(点击) the praise sign. Anyhow, clicking the praise sign _____ that you agree with someone or praise someone. Dianzan is a kind of Chinese Internet language. People _____ use it when they surf the Internet. There is a function of Dianzan in the QQ space. The QQ space has had the function _____ 2010. It didn't become very popular until Sina blog(新浪博客) _____ the function of dianzan. In recent years, it has become mor 某公司销售一种新型节能产品，现准备从国内和国外两种销售方案中选择一种进行销售．若只在国内销售，销售价格y(元/件)与月销量x(件)的函数关系式为y＝－x＋150，成本为20元/件，无论销售多少，每月还需支出广告费62500元，设月利润为w内(元)(利润＝销售额－成本－广告费)． 若只在国外销售，销售价格为150元/件，受各种不确定因素影响，成本为a元/件(a为常数，10≤a≤40)，当月销量为x(件)时，每月还需缴纳x2元的附加费，设月利润为w外(元)(利润＝销售额－成本－附加费)． (1)当x＝1000时，y＝________元/件，w内＝________元； (2)求出w外与x间的函数关系式(用含a的式子表示，不必写x的取值范围)； (3)当x为何值时，在国内销售的月利润最大？ (4)如果某月要将5000件产品全部销售完，请你通过分析a的取值，帮公司决策选择在国内还是在国外销售才能使所获月利润较大？