美国托福学科真题文本220篇.pdf

® based listening exercises (lectures) – Answer keys TOEFL listening lecture 1 Narrator Listen to part of a lecture in biology class. Prof: Youve been reading about animal behavior. Today well discuss one of the most astonishing behaviors in the animal world: dancing bees. Did you know that bees can dance? Well, neither did scientists, until the 1960s. Thats when a German scientist, named, uh, Karl von Frisch, noticed something truly remarkable. As he was observing honeybees, he noticed that some of the bees, which he called scout bees, flew out of the hive to look for food. When a scout found a site where there was food, it flew back to the beehive and started dancing. This dance somehow told the other honeybees where the food was, because after the dance, the bees... [false start] some of the bees flew from the hive straight to the site of the food. Von Frisch called the bees that collect the food forager bees. He thought the scout bees dance told the forager bees three things -- first, the smell of the food it had found; second, which direction to fly to reach the food; and third, the distance of the food site from the beehive. Von Frisch won the 1973 Nobel Prize for this discovery, but many scientists were skeptical of his theory. They didnt believe it was the dance that led the forager bees to food. Instead, they thought it might be, oh, the smell of the food on the dancing bee, or maybe that they just followed the scout back to the food site. Well, very recently, some British scientists used a new type of radar to prove that von Frischs theory was indeed correct. It is the dance that communicates this information to other bees. The British researchers found that scout bees perform two types of dances. If the food is near the hive, say, oh, about 50 or 60 meters away, the scout flies in a round pattern, like a circle. This tells the location, but not the direction, of the food site. If the site is farther away,