Question

【題目】 We all enjoy the colors of autumn leaves. Did you ever wonder how and why a leaf changes color? Where do the yellows and oranges come from? To answer those questions, we first have to understand what leaves are and what they do.

Leaves are the world's food factories. Plants take water from the ground through their roots and take CO2 from the air. Plants use sunlight to turn water and CO2 into glucose(葡萄糖), a kind of sugar. Plants use it as food for energy and growing.

A chemical called “chlorophyll(葉綠素)” in the leaves gives plants their green color. As summer ends and autumn comes, the days get shorter and shorter, and trees “know” it's time to begin getting ready for winter.

During winter, there is not enough sunlight or water. Trees rest during this time and live on the food they store during the summer. They begin to shut down their foodmaking factories. As the green chlorophyll disappears from the leaves, we begin to see yellow and orange leaves.

The bright reds and purples we see in leaves are made mostly in autumn. In some trees, like maples(楓樹), sunlight and the cool nights of autumn turn the glucose in the leaves into a red color. And we can enjoy the beautiful red leaves during autumn.

【1】Which of the following can you put in the box?

sunlight ＋ ＋ CO2 → glucose

A.waterB.sugarC.windD.air

【2】Why do the leaves turn yellow in autumn?

A.Because they are short of glucose and energy.

B.Because they are short of sunlight and water.

C.Because they are short of sunlight and CO2.

D.Because they are short of water and CO2.

【3】Which of the following is NOT true according to the passage?

A.When autumn comes, the days get shorter and shorter.

B.During winter, trees live on the food they store in summer.

C.Trees begin to stop making food and to have a rest in summer.

D.During winter, some of yellow and orange colors are still in the leaves.

【4】What's the main idea about the passage?

A.It tells us all kinds of plants on the earth.

B.It tells us the plants can grow well with the sunlight.

C.It tells us maple leaves change the color as other trees.

D.It tells not all the colors of the leaves are from chlorophyll.

Answer 1

【答案】

【1】A

【2】B

【3】C

【4】D

【解析】

本篇文章難度適中，主要講述五顏六色的樹葉形成的原因。主要講述兩種原因：一種是葉綠素一種是葡萄糖。

【1】細(xì)節(jié)理解題。根據(jù)Plants use sunlight to turn water and CO2 into glucose(葡萄糖), a kind of sugar“植物利用陽光將水和二氧化碳轉(zhuǎn)化為葡萄糖，一種糖”可知，陽光和水和二氧化碳轉(zhuǎn)化為葡萄糖，故選A。

【2】細(xì)節(jié)理解題。根據(jù)During winter, there is not enough sunlight or water. Trees rest during this time and live on the food they store during the summer. They begin to shut down their foodmaking factories. As the green chlorophyll disappears from the leaves, we begin to see yellow and orange leaves“在冬天，沒有足夠的陽光和水。樹木在這段時(shí)間休息，靠夏天儲存的食物生存。他們開始關(guān)閉食品制造廠。當(dāng)綠色的葉綠素從樹葉中消失時(shí)，我們開始看到黃色和橙色的樹葉”可知，因?yàn)槿鄙訇柟夂退�，故選B。

【3】細(xì)節(jié)理解題。根據(jù)As summer ends and autumn comes, the days get shorter and shorter“因?yàn)橄奶旖Y(jié)束秋天到來，白天變得越來越短”，排除A；根據(jù)Trees rest during this time and live on the food they store during the summer“樹木在這段時(shí)間休息，靠夏天儲存的食物生存”可知，樹靠夏天儲存的食物為生，排除B；根據(jù)As the green chlorophyll disappears from the leaves, we begin to see yellow and orange leaves“當(dāng)綠色的葉綠素從樹葉中消失時(shí)，我們開始看到黃色和橙色的樹葉”可知黃色和橙色的樹葉仍在樹上，排除D；根據(jù)During winter, there is not enough sunlight or water. Trees rest during this time and live on the food they store during the summer. They begin to shut down their foodmaking factories“在冬天，沒有足夠的陽光和水。樹木在這段時(shí)間休息，靠夏天儲存的食物生存。他們開始關(guān)閉食品制造廠”可知，在冬天他們開始停止生產(chǎn)食物并且休息，而不是在夏天，故選C。

【4】推理判斷題。根據(jù)As the green chlorophyll disappears from the leaves, we begin to see yellow and orange leaves“當(dāng)綠色的葉綠素從樹葉中消失時(shí)，我們開始看到黃色和橙色的樹葉”以及The bright reds and purples we see in leaves are made mostly in autumn. In some trees, like maples(楓樹), sunlight and the cool nights of autumn turn the glucose in the leaves into a red color. And we can enjoy the beautiful red leaves during autumn“我們在樹葉中看到的明亮的紅色和紫色主要是在秋天制造的。在一些樹上，像楓樹，陽光和秋天涼爽的夜晚把樹葉中的葡萄糖變成紅色。我們可以在秋天欣賞美麗的紅葉”可知，不是所有的樹葉的顏色都來自葉綠素，故選D。