普通阅读3{:E;D+p6h'V6s5g
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 to turn water and CO2 into glucose. 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. That means "putting together with light.” A chemical called chlorophyll helps make photosynthesis happen. Chlorophyll is green. It gives plants their green color.3{:E;D+p6h'V6s5g
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.3{:E;D+p6h'V6s5g
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.3{:E;D+p6h'V6s5g
4[-v+h*V'z;G0p 1. The word "chlorophyll" in the first paragraph means ________ in Chinese.3{:E;D+p6h'V6s5g
A.叶绿素3{:E;D+p6h'V6s5g
B.氧气3{:E;D+p6h'V6s5g
C.胡萝卜素3{:E;D+p6h'V6s5g
D.蛋白质3{:E;D+p6h'V6s5g
8T9M+K7L 2. Where is CO2 from?3{:E;D+p6h'V6s5g
A. Ground.3{:E;D+p6h'V6s5g
B. Roots.3{:E;D+p6h'V6s5g
C. Sunlight.3{:E;D+p6h'V6s5g
D. Air.3{:E;D+p6h'V6s5g
5]:n(M-f1}*B.H4x5z)m 3. The way ________ is called photosynthesis.3{:E;D+p6h'V6s5g
A. plants get CO2 from the air3{:E;D+p6h'V6s5g
B. plants take water from the ground3{:E;D+p6h'V6s5g
C. plants turn water and CO2 into glucose3{:E;D+p6h'V6s5g
D. plants use glucose as food for energy to grow3{:E;D+p6h'V6s5g
'o:D:T/n*X2H 4. Red and purple colors in leaves are made mostly in ________ .3{:E;D+p6h'V6s5g
A. spring3{:E;D+p6h'V6s5g
B. autumn3{:E;D+p6h'V6s5g
C. summer3{:E;D+p6h'V6s5g
D. winter3{:E;D+p6h'V6s5g
1G*O/]'H0q4R)B;P;|:l)M8Y+D)Q'h,[ 5. what in the leaves changes into red color in autumn.3{:E;D+p6h'V6s5g
A. Sunlight3{:E;D+p6h'V6s5g
B. Water3{:E;D+p6h'V6s5g
C. Glucose3{:E;D+p6h'V6s5g
D. Chlorophyll3{:E;D+p6h'V6s5g