听力原文： Most economic forecasts are wrong. And governments usually fail when they try to fine-tune the economics in the short term. That's not surprising, argues Paul Ormerod in his book Butterfly Economics, because few underlying economic theories and models come anywhere near real life. Ormerod, an economist and director of the London Think Tank, has dumped on the blinkered world of mainstream economic thought before, in his book, The Death of Economics. This time, he argues that his colleagues with the dismal science should instead view "society as a living creature, which adapts and learns."
Ormerod calls his approach butterfly economics, in part to stress its link to biology. But it also reflects a principle advanced by chaos theorists that the fluttering of a butterfly's wings can set off a tornado in another part of the globe. Modem economics, he says, are "complex systems which hover on the brink of chaos." But Ormerod could just as easily have titled it Ant Model Economics, because his theories derive from entomologists' experiments with ants in the mid-1980s. Two equal-sized food sources were set equidistant from an ant's nest. How did the colony divide itself between the sources？ As it turned out, the proportion of ants visiting one site or the other changed constantly. Sometimes changes were small. Other times, shifts were dramatic and swift. None was predictable. Why？ Basically, a foraging ant has three choices: returning to the food source it successfully visited before; being persuaded by other ants, via a scent, to try the other pile; or turning to the humans. People can stick with a previous decision, change their minds on their own accord, or be persuaded by the actions of others.
That people are often influenced by others, the author says, goes a long way toward explaining why some inferior technologies squeeze out superior ones, like VHS videocassette recorders upstaging Betamax VCRS, or why traders continue to buy currencies they know to be overvalued. Popularity breeds popularity. This may all seem obvious. But for economists, it's a revelation. Standard economic theories nearly always assume that people's behavior. and tastes never change -- which helps explain why most theories can't pass a reality check. In real life, chaos -- in the form. of human decision making -- reigns.
The ant model shows that accurate short-term predictions of ant behavior. are impossible. But in long term, there is a pattern to the ants' randomness. And, Ormerod says, so it is with economics, too. Short-term governmental forecasts usually miss the mark. And the abilities of politicians to alter the cycles of business are" largely illusory," he insists. But in the long term, there is some structure. The business cycle, with all its constant ebbing and flowing, may be uncontrollable and defiant of near-term forecasts. But despite its fluctuations, capitalist economies have grown slowly and steadily over time. That means, he says, that policymakers should adopt a less-is-more approach. "The role of governments should be confined to trying to mitigate the consequences of a cycle rather than trying to eliminate it."
Ormerod's effort to persuade orthodox economists to take human behavior. into account more often -- regardless of its unpredictability -- is a worthy goal. Still, it's a bit dispiriting that his foraging ants, like Pavlvov's salivating dogs, depict our behavior. so accurately.
Listen to the following passage. Write in English a short summary of around 150-200 words of what you have heard. You will hear the passage only once and then you will have 25 minutes to finish your summary. This part of the test carries 20 points. You may need to scribble a few notes to write your summary.