题目

 The Internet is full of headlines that grab your attention with buzzwords （流行词）．But often when we click through, we find the content hardly delivers and it wastes our time．We close the page, feeling we've been cheated．These types of headlines are called click bait．     A headline on Busing, reconsider．com reads:  This phrase will make you seem more polite．First, when you click through, you find another headline: Four words to seem more polite． Then, on reading the article, you find it's actually an essay about sympathy．And what are the four words? The5．大小相等的长方形瓷砖，每块长15厘米，宽10厘米，要把它们拼成一个大正方形．拼成大正方形的边长最小是多少厘米？