题目

Mark and Sophie are good friends. They both like animals.It is Sunday today. It's warm and ______, so they decide to take a walk to the city zoo.When they reach, they first go to the ______ cage. They want to see a new lion. She is there ______ only three weeks. She is very beautiful. She has big brown eyes. When the lion ________Mark and Sophie, she opens her big mouth and shows her ______ to them.Sophie asks Mark to go to the monkeys' area. She buys bananas and feeds them slowly. They are very funny. They______ up and down a lot.Then they go to the snakes'（蛇的）area. Sophie feels afrai以下说法中正确的是（　　）A．某种昆虫靠翅的振动发声．这种昆虫的翅在2 s内做了700 次振动，则频率是350 Hz，人类能听到B．多数情况下，声音在气体中的传播速度比在液体中快，在固体中的传播速度比在液体中快，声音在空气中的传播速度受温度影响C．在筷子上捆一些棉花（或碎布），做一个活塞．用水蘸湿棉花后插入两端开口的塑料管或竹管中．用嘴吹管的上端，可以发出悦耳的哨音．上下推拉“活塞”，音调就会改变D．在噪声较大的环境中工作时，人们常佩戴耳罩，属于在声源处减弱噪声