今天及解析Lecture1，主要内容是
TPO43 听力 Lecture 1
1. What is the main purpose of the lecture? 【主旨目的题】
A To explain how the red pigment in leaves breaks down
B To show that leaf color varies based on the tree species
C To introduce a theory about why leaves turn a particular color
D To explain how chlorophyll protects trees in autumn
答案：C
破题关键词汇：
解析：(从14秒开始，原文重现：So this will be a great time to talk about how and why some of these leaves turn one color in particular and that's bright red.)
此处用So引出本讲座将要展开讨论的话题，为什么某些树叶会变成红色。对应选项C。
2.What does the professor imply when she explains why leaves are green? 【推断题】
A She wants to correct a common misconception about the topic.
B She thinks the students are probably already familiar with the material.
C She believes the process is too complicated to discuss in depth.
D She knows that students are often confused about the functions of chlorophyll
答案：B
破题关键词汇： leaves are green
解析：(从23秒开始，原文重现：Well, before we discuss why leaves turn red, first, let's, um, look, I know this is very old material, but just to play it safe, let's first go over why leaves are usually green. It's chlorophyll, right?)
此处教授提到I know this is very old material，It's chlorophyll, right?可以推断出这是学生已经知道的内容，也就是叶绿素造成树叶呈现绿色。对应选项B。
3. What does the professor mean when she says that the classic theory is partially right? 【目的题】
A It describes what happens in the summer but not what happens in autumn
B It describes what happens in tree leaves but not what happens in leaves of other plants
C It explains how pigments are synthesized but not how they break down.
D It explains some cases of color change in tree leaves but not all cases.
答案：D
破题关键词汇： partially right
解析：(从1:39秒开始，原文重现：OK, so that's the classic explanation and it's partially right. Why do I say partially? Well, it's probably true for pigments like yellow or orange, but it doesn't seem to hold for the red pigment.)
此处提到传统解释只是部分正确的，接着接受进行了解释，这种说法可以适用黄色或角色但红色不行。说明不适合所有情况，对应选项D。
4. Why does the professor mention painting a car? 【目的题】
A To question why a large amount of anthocyanin is produced just before leaves fall
B To explain why most leaves turn red instead of other colors
C To remind students how cooler temperatures affect the color of leaves
D To show how anthocyanin absorbs sunlight to produce food for trees
答案：A
破题关键词汇： painting a car
解析：(从2:50秒开始，原文重现：It'd be likes spending money to...I don't know...to have your old car repainted when you know the car's not going to last more than a couple of months. All this extra anthocyanin in the autumn seems like a waste.)
此处用例子来说明树叶中的花青素看起来很浪费，上文提到在叶片快要凋零时树木生成了大量花青素，对应选项A。
5. The professor mentions theories about why leaves turn red that involve predatory insects and fungi. What is her opinion about those theories? 【态度题】
A They are based on careful research.
B They do not completely explain the phenomenon.
C They have not received enough attention.
D They have been proved to be incorrect.
答案：B
破题关键词汇： predatory insects and fungi
解析：(从3:20秒开始，原文重现：One of them involves predatory insects; another involves fungi. You know, the more I read about these theories and the related research, it always created more questions for me than answers. So I was really glad to learn about a totally different theory, a new one. It seems to come with research and data that give a full explanation. So here it is.)
此处没有直接回答捕食性昆虫或真菌类与树木生成的花青素之间的关系，对应选项B。
6. According to the professor, why does anthocyanin appear on the upper side of some leaves? 【细节题】
A To help chlorophyll absorb the sunlight
B To maximize the leafs utilization of sunlight
C To accelerate the breakdown of chlorophyll
D To protect an important process from the sunlight
答案：D
破题关键词汇： upper side
解析：(从4:34秒开始，原文重现：The theory is that anthocyanin protects the reabsorption process from the sunlight. For example, if you look closely at a red leaf on a tree, you'll notice that most of the red pigment is on the upper side of the leaf, the side facing the sun. This new theory suggests that what the anthocyanin is doing there on top is shielding the rest of the leaf from the sunlight, and more importantly, allowing those important chemicals to be reabsorbed by the tree.)
此处开头就提到protects the reabsorption process，接着用例子来进行解释，红色色素大部分都在树叶的上侧，面对太阳，对应选项D.
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