SAT閱讀詞條講解：聲納和海豚

　　下面小編為大家整理了SAT閱讀考試中的文化詞條賞析，關(guān)于聲納和海豚的，供大家學(xué)習(xí)，大家平時也可以多關(guān)注和積累，自己搜集整理一些SAT閱讀文章詞條，幫助自己更好地備考SAT閱讀考試。

　　請看以下兩個SAT閱讀文章詞條的介紹：

　　1、Dolphins

　　Dolphins are marine mammals that are closely related to whales and porpoises. There are almost forty species of dolphin in seventeen genera. They vary in size from 1.2 meters and 40 kilograms, up to 9.5 m and 10 ton. They are found worldwide, mostly in the shallower seas of the continental shelves, and are carnivores, mostly eating fish and squid. Dolphins are considered to be amongst the most intelligent of animals and their often friendly appearance and seemingly playful attitude have made them popular in human culture.

　　海豚一種與鯨和鈍吻海豚很接近的海洋哺乳動物，包括17屬近40種。海豚體型差異大，從身長1.2米體重40千克到身長9.5米體重10噸不等。海豚遍布世界各地，主要在淺海大陸架活動。屬食肉動物，主要食物是魚類和魷魚。海豚被認為是自然界智商最高的動物之一。因其友善的外表和貌似活潑的天性，被看作人類的好友。

　　2、Sonar

　　Sonar is a technique that uses sound propagation (usually underwater) to navigate, communicate or to detect other vessels. Sonar may be used as a means of acoustic location. The term sonar is also used for the equipment used to generate and receive the sound. The frequencies used in sonar systems vary from infrasonic to ultrasonic.

　　聲納一種利用水下聲音傳播來導(dǎo)航，聯(lián)絡(luò)或偵查其他船只的技術(shù)。它可用于聲音定位。這個術(shù)語還指產(chǎn)生和接收聲波的設(shè)備。聲納所使用的頻率從次聲到超聲不等。