单项选择题

Passage 2

Highly intelligent and strong, elephants are the largest land animals and are among the longest-lived, with life spans of 60 years or more. Healthy, full-grown elephants have no natural enemies other than humans. Elephants once lived on every continent except Australia and Antarctica, but elephants today are restricted to Africa and parts of Southeast Asia. They occupy a wide range of environments in Africa and Southeast Asia: grasslands, marshes, forests, deserts, and mountains. They need great quantities of food to support their massive size. They also need a lot of drinking water and so are restricted to areas with adequate water. Throughout history, people have prized elephants for their great size and strength. On the battlefield, elephants have defeated the enemies. Elephants also have been trained to carry heavy supplies through the forests where they once lived. Elephants have long been honored, and in Thailand, India, and other Southeast Asian countries, beautifully decorated elephants still play a significant role in traditional religious ceremonies. Over the past 40 million years, more than 600 species of elephants have lived on the earth. Today only two species are alive: the African elephant and the Asian elephant. Climate changes caused the extinction of many elephant species, but human influence has also taken its toll. At the turn of the 20th century, elephants numbered from 5 million to 10 million, but widespread hunting and city expanding reduced their numbers to an estimated 640,000 by the end of the century. At present, efforts to save elephants may be inadequate, and biologists are unsure if elephants as a species will survive.

 

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