有关信息的传播与信号的应用下列叙述正确的是（　　）

购买加工食品时要注意看生产日期和保质期。（  ）

一辆汽车以30m/s的速度向山崖前进，司机鸣笛后继续前进，5s后听到回声，求司机听到回声时汽车距山崖的距离．（声音在空气中的传播速度是340m/s）

课外阅读。

       今天，我高高兴兴地去游滨海公园。

       我穿过月亮门，首先映入眼帘的是无边无际的碧蓝的大海。今天，风平浪静，浪花顽皮地涌来涌去，海面闪烁着点点金光。我挽起裤腿，脱下谢，欢快地跳进水中。可惜我不会游泳，只好在浅水里呆一会儿。浪花亲热地向我打来，不住的舔着我的腿、我的脚。啊！真舒服。

       我从水里出来，来到左边的长廊。长廊里凉爽极了，清风徐徐，会使人忘掉一切不愉快的事情。

       我穿过长廊的月亮门，啊！前面是一个大喷水池。池的周围有一条“大鲤鱼”和一只“大乌龟”。“鲤鱼”半“站”着，嘴里吐着“泡泡”，“乌龟”则悠闲地趴在那儿。

       水池的旁边有两座滑梯。再远处有几个小亭。我回过头，突然看见长廊正中的月亮门上边写着四个浅绿色的大字：滨海公园。

       ​滨海公园美丽极了，我真想再玩会儿。

任务型阅读

    "Let's go to the petting zoo(抚爱式动物园)!"said Bonk．

    "First,let's get some food for the animals．"said Lurk．

    "I'm so happy we call feed the animals．"said Uzzle．

    "I'll get carrots for the horses．"said Lurk．

    "I'll get cabbages for the chickens．"said Uzzle．

    "I'll get corn(玉米)for the sheep，"said Bonk．

    At the zoo，Bonk put some of the corn in his bag．His bag had a small hole(洞)，but Bonk didn't know about it．Bonk and his friends played with the animals and fed them．Bonk forgot about the corn．

    On the way home，the corn dropped(落下)out．One of the sheep at the zoo followed the corn to Bonk' s home．Before Bonk and his friends said goodbye to each other,they saw the sheep．

    "How do we get him back to the zoo?"asked Bonk．

    Bonk and his friends did everything．But the sheep just didn't move．

    "Mr Sheep，"said Lurk．"You need to go back to the zoo．"The sheep didn't move．

    "I know what will work!"said Bonk．Bonk put the corn along the road to the petting zoo and let the sheep eat it．The sheep moved when he ate the corn．At last．the sheep was back at the zoo．

    "Baa!"said the sheep．

    "You're welcome．"said Bonk．

根据材料内容简要回答下列问题。