We all enjoy the beautiful show of colours as leaves change each autumn. But did you ever wonder how and why this happens?

Leaves are nature’s food factories. Plants take water from the ground through their roots and take carbon dioxide (二氧化碳) from the air. Plants use sunlight to turn water and carbon dioxide into glucose (葡萄糖). Glucose is a kind of sugar, which plants use as food for energy and growing.

The way plants turn water and carbon dioxide into sugar is called photosynthesis that means “ putting together with light”. A chemical called chlorophyll helps photosynthesis. It 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 light or water for photosynthesis. 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. Small amounts of these colours have been in the leaves all along. We just can’t see them in the summer, because they are covered up by the green chlorophyll.

The bright reds and purples we see in leaves are made mostly in autumn. In some trees, like maples (枫树), glucose is caught in the leaves after photosynthesis stops. Sunlight and the cool nights of autumn turn this glucose into a red colour. The brown colour of trees like oaks (橡树) is made from waste left in the leaves.

It is the mixture of all these things that makes the beautiful colours we enjoy during autumn.

1.The word “chlorophyll” in the third paragraph means _______ in Chinese.

A．叶绿素           B．氧气             C．胡萝卜素         D．蛋白质

2.The leaves of the trees in autumn turn yellow because of the short of _____.

A．water and carbon dioxide

B．glucose and energy

C．sunlight and water

D．sunlight and carbon dioxide

3.The way that _______________________ is called Photosynthesis .

A．plants change water and carbon dioxide into sugar

B．plants turn water and carbon dioxide into sugar with the help of sunlight

C．plants use glucose as food for energy and growing

D．chlorophyll is a great help

4.Which of the following is NOT true?

A．When autumn and winter come, the days get shorter and shorter.

B．During winter trees rest and live on the food they store during the summer.

C．During winter small amounts of yellow and orange colours are kept in the leaves all the time.

D．Trees begin to stop making food in summer.

5.This passage tells us __________________.

A．all the plants can grow well with the strong sunlight

B．there are all kinds of plants on the earth

C．all the colours of the leaves aren’t made from chlorophyll

D．maples and oaks have the same reason as other trees for the change of colours

 

When I was growing up, I had an old neighbor, Dr. Gibbs. He didn’t look like any doctor I’d ever known. He never invited us to play in his yard, but he was a very kind person.
When Dr. Gibbs wasn’t saving lives, he was planting trees. He owned a large field and wanted to make it a forest.
The good doctor had some interesting ideas about planting trees. He never watered his new trees. Once I asked why. He said that watering plants spoiled them, and that if you watered them, each baby tree would grow weaker and weaker, so you had to make things difficult for them and pick out the weaker trees early on.
He talked about how watering trees made for shallow（浅的）roots, and how trees that weren’t watered had to grow deep roots in search of water under the earth by themselves. Deep roots were very important.
So he never watered his trees. He’d planted an oak and, instead of watering it every morning, he’d beat it with a rolled-up newspaper. I asked him why he did that, and he said it was to get the tree’s attention.
Dr. Gibbs died several years after I left home. Every now and then, I walked by his house and looked at the trees that I watched him plant about twenty-five years ago. They’re very big and strong now. I planted some trees a few years back and carried water to them for whole summer.
After two years of caring too much, whenever a cold wind blows in, they shake a lot.
Every night before I go to bed, I check on my two sons. Mostly I pray（祈祷）that their lives will be easy. But lately I’ve been thinking that it’s time to change my prayer. I know my children are going to face difficulties. There’s always cold wind blowing somewhere, so what we need to do is to pray for roots that reach deep into the brave heart, so when the rains fall and the winds blow, we could face it strongly and won’t be beaten down.
【小题1】We know from the passage the doctor           .

A．didn’t know how to plant trees at all

B．wasn’t good at his own medical job

C．had his own ways of planting trees

D．had nothing to do but plant trees

【小题2】When Dr. Gibbs said “…pick out the weaker trees early on.”, he meant that          .

A．some weak trees would be easily found out at the beginning

B．he would choose the weak trees to water earlier

C．the weak trees would be sent to his patients later

D．he would not plant weak trees so early anymore

【小题3】The passage tells us that the writer      .

A．should beat his trees with a rolled-up newspaper

B．didn’t often water his trees

C．didn’t have a large field

D．took too much care of his trees

【小题4】Which can be the best title of the passage?

A．Watering trees

B．Growing roots

C．Doctor and his neighbor

D．Father and his children

Farmer Ed Rawlings smiles as he looks at his orange trees. The young oranges are growing well in Florida’s weather. Warm sunshine and gentle rains, along with Ed Rawlings’ expert care, will produce a good crop（收成）of oranges this year.

However, Ed has to guard against Florida’s changeable winter weather. In January and February, temperatures can destroy Ed’s entire orange crop. Having farmed in Florida for the past 35 years, Ed is prepared for the frost(霜). When temperatures drop below freezing, Ed tries to save his crop by watering his orange trees. The water freezes and forms a thin layer(层) of ice around the trees. Strange as it may sound, this thin layer of ice actually keeps the fruit warm.

What happens is simple. When the trees are watered, the water loses heat and becomes ice. The warmth of the heat it loses is taken in by the fruit and keeps its temperature at a safe level. Ed has effectively used this method to save many orange crops.

But Ed still faces difficulties. The trees must be watered at the exact moment the temperature drops to the freezing point. Also, just the right quantity(数量)of water must be used. Too much water can form a thicker layer of ice that will break the tree’s branches(树枝). Another difficulty is that wind blows away the heat, so Ed has to worry about not only when but also how often his trees should be watered, and how much water should be used.

Computer technology may help Ed with some of these worries. With equipment(设备), air and soil temperatures and wind speed can be measured. The information is fed into a computer which can calculate(计算) when the temperature will drop below freezing. The computer can correctly decide the quantity of water to be used and how frequently(  ) the trees should be watered. Ed finds looking after his orange trees a lot easier with the help of a computer, and, his customers will have the benefits(利益) of computer—age oranges. 

1.The passage is mainly about______.

A. a farmer expert cares for his orange trees

B. the different uses of computers

C. growing oranges in Florida’s changeable weather

D. different ways of frost protection

2.Ed tries to protect his crop by______.

    A. using a wind machine to drive away the cold air

    B. equipping his orange trees with a computer

    C. watering it at the proper time

    D. picking his fruit at the first sign of frost

3. According to the passage, the computer technology______.

    A. removes the need for frost protection

    B. prevents temperature from dropping

    C. tells farmers why outdoor temperatures change

    D. helps the farmer get a better harvest

 

We all enjoy the beautiful show of colours as leaves change each autumn. But did you ever wonder how and why this happens?
Leaves are nature’s food factories. Plants take water from the ground through their roots and take carbon dioxide (二氧化碳) from the air. Plants use sunlight to turn water and carbon dioxide into glucose (葡萄糖). Glucose is a kind of sugar, which plants use as food for energy and growing.
The way plants turn water and carbon dioxide into sugar is called photosynthesis that means “ putting together with light”. A chemical called chlorophyll helps photosynthesis. It 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 light or water for photosynthesis. 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. Small amounts of these colours have been in the leaves all along. We just can’t see them in the summer, because they are covered up by the green chlorophyll.
The bright reds and purples we see in leaves are made mostly in autumn. In some trees, like maples (枫树), glucose is caught in the leaves after photosynthesis stops. Sunlight and the cool nights of autumn turn this glucose into a red colour. The brown colour of trees like oaks (橡树) is made from waste left in the leaves.
It is the mixture of all these things that makes the beautiful colours we enjoy during autumn.
【小题1】The word “chlorophyll” in the third paragraph means _______ in Chinese.

A．叶绿素

B．氧气

C．胡萝卜素

D．蛋白质

【小题2】The leaves of the trees in autumn turn yellow because of the short of _____.

A．water and carbon dioxide

B．glucose and energy

C．sunlight and water

D．sunlight and carbon dioxide

【小题3】The way that _______________________ is called Photosynthesis .

A．plants change water and carbon dioxide into sugar

B．plants turn water and carbon dioxide into sugar with the help of sunlight

C．plants use glucose as food for energy and growing

D．chlorophyll is a great help

【小题4】Which of the following is NOT true?

A．When autumn and winter come, the days get shorter and shorter.

B．During winter trees rest and live on the food they store during the summer.

C．During winter small amounts of yellow and orange colours are kept in the leaves all the time.

D．Trees begin to stop making food in summer.

【小题5】This passage tells us __________________.

A．all the plants can grow well with the strong sunlight

B．there are all kinds of plants on the earth

C．all the colours of the leaves aren’t made from chlorophyll

D．maples and oaks have the same reason as other trees for the change of colours