[解析]
首先提出问题开始话题,故What are these?(这些是什么?)排第一;其次回答问题,故They are tomatoes.(它们是西红柿。)排第二;然后询问价格,故How much are the tomatoes?(西红柿多少钱?)排第三;接着回答价格,故The tomatoes are one yuan for four.(这些西红柿一元四个。)排第四;最后付钱买下西红柿,故That's fine.I'll take eight.(那很好。我要八个。)排最后。
故答案为:(2)→(4)→→(5)→(1)→(3)。