文档介绍：2013 春《大学英语 4 》综合复习资料 I. prehension Passage 1 For ages, sailors have said that it is good luck to see dolphins swimming alongside boats. Their presence meant that land was near, which would be vital information ifa boat and her crew were in danger. Some dolphins have even protected shipwrecked sailors from sharks. It is no wonder that these unique and fascinating creatures have long been known as our friends. You may think dolphins are fish, but they are actually mammals. They are related to whales and porpoises, and they evolved around 10 million years ago. Dolphins breathe air, give birth to live young, and feed them milk. They are social animals, living together in groups ranging in size of up to places rich in food, many schools bine together to form schools of up to 1,000 dolphins. Dolphins are thought to be intelligent animals because of their playfulness, curiosity, and quick ability to learn. They seem municate with each other through bination of squeaks, whistles, and clicks. While scientists don't know what they are going on about, it is thought that dolphins are telling each other that food is nearby, or warning each other of approaching danger. Dolphins use sonar to discover an object's size, shape, and location. By sending out a series of clicks and receiving the echo that bounces off the object, they can differentiate between a shark and a boat. Unfortunately, dolphins have faced increasing danger in recent years. Fishermen in pursuit of profitable tuna may accidentally trap dolphins in s, killing them in the process. These intelligent mammals of the sea deserve our protection and respect. 1. Dolphins have been human's friends because of ____________. A. sailors may know that the land is not far away B. some dolphins protect sailors from shark attacks C. sailors municate with them D. both A and B 2. Which of the following statement about dolphin is not true? A. Dolphins lay eggs under the sea. B. Dolphins municate with each other by sending out s