来源： 浏览： 发布日期：2020-11-09 13:48
"Take American alligators. If you were to go to a swamp during the breeding season, you'd hear a chorus of sounds, deep grunts, hisses, these are sounds that male alligators make.
And some of them are powerful enough to make the water vibrate. This sends a strong, go-away message to the other males. So the alligator can focus on sending other sound waves through the water, sound waves that you and I couldn't even hear since they are at such low frequency. But they do reach the female alligator, who then goes to find and mate with the male.
Vocalization is um...well, it is used for other reasons..."
通过信号词(take American alligators和used for other reasons)确定这是一个小层次，在笔记中，相信大家都会记下：
1. Send go away messa-> other
2. Reach female(mate)
According to the professor, what are two functions of the sounds made by male alligators? Click 2 answers
To frighten predators
To attract mates
To locate hatchlings
To threaten other males
在选项中常出现极端词汇为：first, second, the most..., new, never, always，而这些词往往是错误选项，我们不需要去过多的考虑
"And with that came increased seasonality, that is, the summers became warmer, and the winters actually became colder. These extreme shifts would have put a lot of stress on the bodies of animals that were used to a more moderate range of temperatures."
"But when the seasons became more distinct, the plant communities were pulled apart, that meant, in any given area, there was less plant diversity. And as a result, uh, so the theory goes, the Ice Age animals that depended on plant diversity couldn't survive."
Extreme temp -> stress -> animal body
Temp-> plant less diversity -> animal not survive
26. According to the climate change theory, how did the climate change at the end of the ice age make it more difficult for large animals to survive? Click on 2 answers
By reducing the size of their habitats
By forcing them to endure a wider range of temperatures
By reducing the variety of food available to them
By forcing them to live near humans
很多时候，我们在听的一知半解的情况下，或者在两个选项中纠结时，需要及时联想起本篇听力的主旨，这样就可以将答案选出。但有时候我们要多依靠每个部分的topic sentence解题。例如(TPO 第二个对话)：
Professor: That's it. Basically. Um... so exactly what is it you don't understand?
Student: OK. I guess what I am really confused about is how the topography of the land, the mountains and valleys and stuff, affects precipitation.
topography -> precipitation
20. What aspect of the hydrologic cycle is the student confused about?
How the process of evaporation works
How topographical features affect precipitation
How water vapor in the atmosphere becomes rain
How lake water fits into the cycle