剑桥雅思12Test7Section4听力答案解析 The effects of environmental change on birds
剑桥雅思12 Test7 Section4听力答案解析
对应原文： So it’s been known for some time that birds which eat fish may be affected, but what wasn’t known until quite recently is that those that eat insects can also be affected.
对应原文：she’s looking for more subtle sub-effects. And these may be to do with the behavior of the birds
答案解析：听到人名意识到录音进行到了第二部分，空前词birds’被替换为of the birds，根据所有格关系，确定答案为behavior。
对应原文：what you may not know is that a young bird seems to acquire this skill by listening to the songs produced by its father, rather than by any other bird.
对应原文： if they eat food contaminated with mercury , then the songs they produce aren’t as complex as those produced by other birds
答案解析：听到mercury意识到答案即将到来。录音原文将题干中的比较级替换为not as … as …的形式，由此确定答案为complex。
对应原文： because it can mean that they’re less attractive to female birds, and so it can affect their chances of reproduction
对应原文：The lab-based studies have the advantage that you don’t get all the variables you would in a natural setting. so the experimenter has a much higher level of control
答案解析：听到lab-based studies意识到答案即将到来，空前词more与a much higher level of同义替换，由此确定答案为control。
对应原文： Well, because many birds are migratory they may be transporting mercury far from contaminated sites. For example, it’s been found that ducks
答案解析：根据migrating与migratory的同义替换意识到答案即将到来，for example与such as对应，由此确定答案为ducks。
对应原文：Well, we also know that in humans, mercury causes developmental delays in the acquisition of language
对应原文：It’s now known that an unborn child can be affected if the food eaten by its mother contains high level of mercury
对应原文：It’s true there are new regulations for mercury emissions from power plants, but these will need billions of dollars to implement, and increase costs for everyone.