- 试题详情及答案解析
- Do you want to know how and why a fall leaf changes color? 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”in the leaves gives plants their green colour. As summer ends and autumn comes, the days get shorter and shorter, and trees “know” 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 food-making 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, sunlight and the cool nights of autumn turn the glucose in the leaves into a red colour. And we can enjoy the beautiful red leaves during autumn.
【小题1】Which should be in the box?
【小题2】The underlined word “chlorophyll” means __________.A．air B．sugar C．water D．wind
叶绿素 B. 脂肪 C.蛋白质 D.淀粉
【小题3】The leaves turn yellow because they are short of(缺少) __________.
【小题4】Which of the following is NOT true?A．water and CO2 B．glucose and energy C．sunlight and water D．sunlight and CO2
【小题5】This passage tells us_____________.A．When autumn comes, the days get shorter and shorter. B．During winter trees live on the food they store in summer. C．During winter some of yellow and orange colors are still in the leaves. D．Trees begin to stop making food in summer. A．the plants can grow well only with the sunlight B．there are all kinds of plants on the earth C．not all the colors of the leaves are from chlorophyll D．maple leaves change the color as other trees - 答案：【小题1】C
【小题2】A
【小题3】C
【小题4】D
【小题5】C- 试题分析：短文大意：叶子是世界食品厂。植物通过自己的根吸收地上的水和空气中的CO2。植物利用阳光将水和CO2转化成葡萄糖。植物用它作为能源和粮食。
【小题1】细节理解题。根据第二段中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.可知植物利用阳光将水和
CO2转化成葡萄糖，所以该选C。
【小题2】词义猜测题。根据本句后半句gives plants their green colour.可知是叶子中一种叫做“叶绿素”的物质吧植物变成绿色的，所以该选A。
【小题3】细节理解题。根据第四段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 food-making factories. As the green chlorophyll disappears from the leaves, we begin to see yellow and orange leaves.的描述可知叶子缺少阳光和水就会变黄，所以该选C。
【小题4】细节理解题。根据第四段中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 food-making factories.可知植物在冬天关闭它们的食物制造厂，所以该选D。
【小题5】主旨大意题。仔细读短文可知不是所有的叶子的颜色都来自叶绿素，所以该选C。
考点：科普类阅读。