Question

Leaves are nature’s food factories. Plants take water from the ground through their roots. They take a gas called carbon dioxide(CO2) from the air. Plants use sunlight(阳光) to turn water and CO2 into glucose（葡萄糖）. Glucose is a kind of sugar. Plants use glucose as food for energy(f&ft) to grow. The way plants turn water and CO2 into glucose is called photosynthesis （光合作用）. That means "putting together with light. ” A chemical called chlorophyll helps make photosynthesis happen. Chlorophyll is green. It gives plants their green color.

As summer ends and autumn comes, the days get shorter and shorter. This is how the trees "know" to begin getting ready for winter. During winter, there is not enough light or water for photosynthesis. The trees will rest, and live on the food they have stored during the summer. They begin to close their food—making factories. The green chlorophyll disappears from the leaves. Then, we begin to see yellow and orange colors. A few of these colors stay in the leaves all the time. We just can’t see them in the summer, because they are covered up by the green chlorophyll. Red and purple colours we see in leaves are made mostly in the autumn. In some trees, like maples(枫树)，glucose is stored in the leaves after photosynthesis stops. Sunlight and the cool nights of autumn turn this glucose into red. The brown color of trees like oaks(橡树) is made from wastes left in the leaves.
( ) 1. What’s the Chinese meaning of the underlined part?

A．叶绿素 B．氧气 C．胡萝卜素 D．蛋白质
( ) 2. Where is CO2 from? A. Ground. B. Roots. C. Sunlight. D. Air.
( ) 3. The way________is called photosynthesis.
A. plants get CO2 from the air B. plants take water from the ground
C. plants turn water and CO2 into glucose D. plants use glucose as food for energy to grow
( ) 4. Red and purple colors in leaves are made mostly in________.
A. spring B. autumn C. summer D. winter
( )5.________in the leaves changes into red color in autumn.

A. Sunlight B. Water C. Glucose D. Chlorophyll

Answer 1

1A  2B  3D  4A  5C