OK, class. Let’s get started. It’s Autumn, right? And if you look around, you’ll see lots of trees changing color from green to yellow, orange and lots of other colors. So this is a perfect time to discuss today’s topic. Why and how do some of these leaves change color…um…particularly to bright red?
But first of all, at the risk of boring you, let’s go over an old material and talk about why leaves are normally green. As you know, leaves get their green color from chlorophyll, the chemical that makes photosynthesis possible. The chlorophyll collects sunlight from the Sun and converts it to sugar, the food for the plants. And it’s this chlorophyll that makes the leaves look green most of the time.

중략

OK, so, that’s the classic explanation and it’s partially right. Why do I say partially? Well, if we’re only talking about pigments like orange or yellow, there shouldn’t be any problem with the classic theory. But it doesn’t seem to hold true for the red pigment.
생략

1. What is the main purpose of the lecture?

A. To explain how trees can protect themselves against cold weather
B. To explain how red pigment in leaves breaks down
C. To introduce a theory about why the color variation of leaves never takes place in a particular tree species
D. To introduce a theory about why leaves turn a particular color

[유형] Main Idea Q

[해설]
- 이 지문은 도입부가 비교적 간단한 편이다. 지난 시간의 topic에 대한 언급 없이 바로 today’s topic을 언급하고 있다.
- 도입부의 교수님의 질문은 main idea 의 signal 이라고 할 수 있겠다.
- 도입부의 “Why and how do some of these leaves change color…um…particularly to bright red?” 에서 답이 나왔다.

[정답] D

[오답분석]
- A는 too broad한 내용이다. 그리고 B와 C는 언급하지 않았다.