背诵为王第四册第51课 Dolphins

Lesson51 Dolphins
Some people think that dolphins have a real language and that if we could learn their language; we could eventually start talking to them and discussing the important news of the day.
Sadly, this is only a dream. They may have very big brains and they may make lots of strange noises, but they do not, if we are honest about it, have a true language. It is nice to think they do, but it is simply not the case.They do, however, have a very special talent for using their noises to find their way about the oceans and to locate shoals of fish. This is a kind of sonar - an echo-location system. What happens is that the dolphin swims along, chirping and squeaking, and these very high-pitched sounds spread through the water until they hit some solid object. Then the sound-waves bounce back to the dolphin. The animal can tell how far away the object is by checking how long it takes for the sound to reach him. This feature of sound detection is copied by human beings onto some devices used in submarines, helping them to locate objects and avoid collisions.
With all its special qualities, it is easy to see why we find the dolphin so attractive. It has graceful movement, it is intelligent, it is helpful to those in trouble, it has a playful character and it has a face that always looks happy.
These are all qualities we admire in human beings, so it is not surprising that we are so fond of the dolphin.

shoal 鱼群
chirp 吱喳而鸣
squeak 发吱吱声

海豚
有些人认为海豚有真正的语言，如果能学会它们的语言，我们就能最终和它们交谈，谈论当今重要的新闻。可惜的是，这只是一个梦想。海豚拥有很大的大脑，能够发出许多奇怪的声音，但是老实讲，它们并不拥有真正的语言。能这样认为固然不错，但这不是事实。
然而，海豚确实有特殊的才能，可以利用它们发出的声音在大海里探路和确定鱼群的位置。这是一种声纳装置，一种回声定位系统。具体来讲，海豚边游动边发出嘁嘁喳喳的声音，这些音调很高的声音在水里传播，碰上坚硬的物体后，声波就返回到了海豚。通过声音返回所需的时间，海豚就能确定物体有多远。人类模仿海豚这种声音探测的特征发明了一些潜水艇用的定位和避免碰撞的装置。
海豚具有如此多独特的品质，那就不难理解它为什么那么惹人喜爱了。它动作优雅，聪明伶俐，乐于帮助处于危难之中的人，它生性好玩，还有一张看上去总是很快乐的脸。这些都是我们人类崇尚的品质，所以我们如此喜欢海豚就一点也不奇怪了。