Lecture 3(Environmental Science)
1. What is the main purpose of the lecture?
a. To argue that carbon emissions today are not the only factor responsible for global warming
b. To provide evidence that rates of global carbon emissions fluctuate over time
c. To show the importance of distinguishing between different types of carbon emissions
d. To describe different ways carbon is removed from the atmosphere
(从第54秒开始，原文重现：So we are gonna focus today on the difference between good, bad and well the not so bad, the potentially OK carbon burning.)
2. What aspects of outer space does the professor emphasize?
Click on 2 answers.
a. Its vastness
b. Its cold temperatures
c. The absence of life there
d. Its role as the ultimate source of energy on Earth
答案： B, C
(从第1分50秒开始，原文重现：Because without carbon and other greenhouse gases, our planet will be the same temperature as outer space, around four degrees above absolute zero. And there’s nothing going on at that temperature, no possibility of life of any sort.)
3. According to the professor, how do the oceans remove carbon from the atmosphere?
Click on 2 answers.
a. By dissolving it
b. Through a process of condensation and precipitation
c. By storing the remains of marine animals
d. Through the regulation of air temperatures
答案： A, C
破题关键词汇：oceans remove carbon
(从第2分24秒开始，原文重现：Also, it dissolves in the oceans. Or get stored, deep in the ocean. You have shellfish that use the CO2 dissolve in the water to make carbon in shells, and when they die, they fall to the ocean floor.)
4. Why does the professor mention mining?
a. To explain why the price of fossil fuels is continually rising
b. To explain how certain fuel sources can be recovered from the ocean floor
c. To explain why coal and oil are more difficult to obtain than natural gas
d. To explain why fossil fuels contribute to an excess of carbon in the atmosphere
(从第3分06秒开始，原文重现：These substances are all mine. We have to dig them up or drill a well to release them. And this is carbon that was in the atmosphere millions of years ago. So what happens is when we burn this carbon, ok it doesn’t really release a whole lot compare to the amount that’s already there in the atmosphere, but it adds to the pool. And over year, it accumulates.)
5. What does the professor mean when he refers to biomass carbon as "current carbon"?
a. It is the fuel source most widely approved by environmentalists today.
b. It is part of a balanced system of carbon emission and absorption.
c. It is circulated throughout the oceans by the movement of ocean water.
d. It readily combines with other carbon molecules to produce long chains.
(从第4分10秒开始，原文重现：Biomass carbon is what we might call current carbon. It’s always going in and out of the atmosphere. So if we burn one of these fuels, we are putting its carbon into the atmosphere right? But in a balanced system somewhere else in the world the same amount of carbon is going back. It gets taking in by growing vegetation.)
根据原文，教授提及current carbon的意思是说在一个平衡的系统中，释放出的碳含量和被吸收的碳含量其实是相同的，所以 B选项正确。
6. Why does the professor say this
a. To let students know that the term “greenhouse effect” will be tested
b. To indicate that the definition of “greenhouse effect” will be discussed
c. To suggest that his previous definition of “greenhouse effect” was imprecise
d. To acknowledge that there is controversy surrounding the use of the term “greenhouse effect”
破题关键词汇：But let’s make sure anyway.
(从第14秒开始，原文重现：Everyone knows what that is, right? But let’s make sure anyway.)
教授说But let’s make sure anyway的意思就是暗示学生，接下来会把之前说的温室效应这个概念再介绍一遍，所以 B选项正确。