一个三角形的周长为81cm，三边长的比为2：3：4，则最长边比最短边长​ ____

根据下面图表内容和文字表述，回答下面问题。

我国二氧化硫【注】的排放及贡献率

【注】二氧化硫与空气中其他污染物进行复杂的大气化学反应，形成硫酸盐、硝酸盐二次颗粒，由气体污染物转化为固体污染物，成为PM2．5升高的最主要因素，从而导致雾霾天气的产生。

    Many people think it is very exciting and admirable(令人羡慕的) to be an actor. The actors often wear the most beautiful and fashionable clothes and they can make a lot of money. Many people like them and they have so many fans. But in fact, the job of an actor can be very tiring and hard. To make good movies, for example, action movies, the actors need to go to some remote(偏远的) places. There they don't have good places to stay or nice food to eat. They often have to get up early and go to bed very late. When they are too busy, they don’t have time to sleep or relax. It's very hard.

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