Lesson 7-2 Bats
Every solid object will reflect a sound, varying according to the size and nature of the object. A shoal of fish will do this. So it is a comparatively simple step from locating the sea bottom to locating a shoal of fish. With experience, and with improved apparatus, it is now possible not only to locate a shoal but to tell if it is herring, cod, or other well-known fish, by the pattern of its echo.
It has been found that certain bats emit squeaks and by receiving the echoes, they can locate and steer clear of obstacles -- or locate flying insects on which they feed. This echo-location in bats is often compared with radar, the principle of which is similar.
shoal /ʃoʊl/ 鱼群
comparative /kəmˈpærətɪv/ 比较的;相比的;比较而言的;
herring /ˈherɪŋ/ 鲱鱼
cod /kɑːd/ 鳕鱼;
pattern /ˈpætərn/ 图案;模式;方式
squeak /skwiːk/ 吱吱声;尖叫声
emit /iˈmɪt/ 发出;射出;散发
steer /stɪr/ 掌控方向盘;行驶;操纵; steer clear of 避开
obstacle/ˈɑːbstəkl/ 障碍;阻碍;绊脚石;
radar /ˈreɪdɑːr/ 雷达
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