无论休闲，娱乐、上学、工作，自行车都是人们最喜爱的交通方式之一。因为自行车相对而言有很多优点，例如方便、便宜、易停放、节约能源、没有污染而且可以强壮身体等。很多中学生也爱骑自行车上学，但骑自行车也有一定的风险，所以中学生骑自行车时要遵守一定的交通规则，注意安全。
请根据以上提示，写一篇短文，谈谈骑自行车的优点以及怎样保证骑自行车时的交通安全。
要求：（1）不可逐句翻译，卷面整洁，内容通顺；
（2）90词左右，文章开头已给山，不计入字数；
（3）提示词，convenient（方便）
    The bicycle is one of the most popular vehicles in the word.Why are they so popular？
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【考点】交通．

【答案】The bicycle is one of the most important vehicles in the world.It has many advantages.It's cheap and easy to park bicycles.Bicycle riding can help us save energy and it is good for the environment because bicycle doesn't cause air pollution.Bicycle riding is also good exercise.It helps people become fit and makes the riders' hearts and lungs strong.
Bicycle is becoming more and more popular with the students，but every year many students get hurt in bicycle accidents.So first of all，we should obey the traffic rules.jye.ai we ride a bicycle，we should wear a helmet.If we ride a bicycle at night，we'd better wear light-colored clothes or have lights on our bicycle.It's good to learn more about  traffic signals and first aid.If we follow these suggestions，we will be safer.