根据所学知识回答：
（1）鱼所以能在水中生活，最重要的两个因素是：一是能在水中____ ，二是能靠____ 来获取食物和逃避敌害。观察鲫鱼时，我们看到鲫鱼的身体呈____ 形，这种体形在它游泳时可以起到减小____ 的作用。
（2）与家兔相比，蚯蚓不能快速运动的原因是只有肌肉没有____ 。
（3）在观察蚯蚓的实验中，要保持蚯蚓体表的湿润，其原因是____ 。
（4）青蛙是两栖动物，其幼体生活在水中用____ 呼吸；成体水陆两栖生活，用____ 呼吸，同时用皮肤辅助呼吸。

根据材料内容，选择正确答案。

    Prana was a beautiful dog, whose name means “breath of life”. Although he died several years ago, I can still remember the days we spent together and what he has taught me about love.

    I have two apple trees in the garden. Prana loved apples. When he went outside, he'd catch an apple and take it into the house to eat later. The apples had been on the ground and were often dirty so I wasn't always happy that Prana had brought them into the house.

It was an autumn day in America, but it was very cold. A big snow fell and we had not done anything for its coming. On that special day, Prana went outside and I watched him through the window. I noticed that he was madly digging(挖) holes and bringing the apples to the ground so they could be seen above the snow. I did not know why he was doing this. He seemed to want to do something special.

    When I called him back, he had his usual one apple in his mouth. About five minutes later, I looked outside. The garden was completely covered with birds. Prana had dug up all those apples for his bird friends to eat. He knew that they wouldn't have stored enough food for the coming winter!

李某想购买一辆标价为15万元的汽车，在已有7万元存款的同时，李某又向银行贷款8万元。其中15万元是这辆车的________，李某支付给汽车销售商的7万元存款和还给银行的钱款其职能分别是________和________。(　　)

作文：
        任选一题作文。
       （1）爱在左，情在右，走在生命的两旁，随时播种，随时开花。有泪可流，却不是悲凉……花季的经历，我们学会了取舍与分享，懂得了感恩和担当。绘如花岁月，悟成长真谛。

        请以“成长不烦恼”为题，写一篇文章。
       （2）             在一起
        写作要求：①若选题（2），请在横线上填入恰当的短语，完成题目，然后写作；②立意自定，除诗歌外，文体不限；③有真情实感，不得套用与抄袭；④不得透露个人的相关信息；⑤书写工整，不得少于600字。

如图，双曲线y= $\frac{k}{x}$ 经过Rt△OMN斜边上的点A，与直角边MN相交于点B，已知OA=2AN，△OAB的面积为5，则k的值是____