Study on dolphins` behaviour

00:00:01,240Part four. 00:00:07,500You are now going to hear a lecture about the behavior of dolphins. First, you have some time to look at questions thirty-one to forty. 00:00:41,160Now listen and answer questions thirty-one to forty. 00:00:47,220Okay. Today's lecture is about the behavior of dolphins. Dolphins are mammals closely related to whales and porpoises. There are almost forty species of dolphin, and they vary in size from one point two meters and ninety pounds up to nine and a half me...