SAT閲讀詞條講解

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。海豚遍佈世界各地，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 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.