题目

Happiness is important for everyone. Most people want to be happy, but few know how to find happiness. Here is a story to help you.Once a bird lived unhappily. So it traveled far away to look for its happiness.It flew and flew. Suddenly it saw a spider climbing up a wall. The spider fell off the wall halfway. But it kept climbing again and fell off again. Even so, the spider didn’t give up. The littlebird asked the spider in surprise. “Why don' t you have pain but happiness on your face though you fail again and again?”“Because I keep making my efforts. I'm happy.” said the spider.Th17．5月份的原野，回荡着进入繁殖季节的布谷鸟“布谷…”的叫声．“布谷、布谷，种豆播谷．”这句古老的农谚将布谷鸟跟豆、谷联系到了一起．下面让我们从生物学的角度，进一步寻找这两者之间的关联．（1）布谷鸟的繁殖与豆、谷的播种在同一时节进行，这不是偶然事件，影响这两者共同的环境因素主要是温度．（2）布谷鸟鸣叫是繁殖行为中的求偶行为，豆、谷种子中的胚由受精卵发育而来，这说明布谷鸟与豆、谷的生殖方式都是有性生殖（3）在豆、谷田中，布谷鸟以蝗虫等昆虫为食，是害虫的天敌，请据此写出一条食物链．豆→蝗虫→布谷鸟（或谷→蝗虫→布谷鸟）．