Have you ever noticed the colour of the water in a river or stream after a heavy rainfall? What do you think caused this change in colour? It is soil that has been washed into the river from the riverbank or from t}le nearby fields．

Components of Soft

Soil is made up of a number of layers（层），each having its own distinctive colour and texture．The upper layer is known as the litter．It acts like a blanket．limiting temperature changes and reducing water loss．The topsoil layer is made up of small particles of rock mixed with rotten plant and animal matter called humus（腐殖质），which is black and gives the topsoil its dark colour．This layer is usually rich in nutrients，oxygen，and water．Below the topsoil is the subsoil，a layer that contains more stones mixed with only small amounts of organic matter．This layer is lighter in colour because of the lack of humus．Beneath the soil lies a layer of bedrock．

Soil forms from the bottom up．Over time bedrock is attacked by rain, wind，frost, and snow．It is gradually broken down into smaller particles in a process called weathering．Plants begin to grow，and rotten materials enrich the topsoil．Most of the soil in Eastern Canada．for example．Was formed from weathered rock that was exposed when the ice disappeared l2．000 years ag0．

Water Beneath the Soil

Surface water collects and flows above the ground in lakes．ponds．and rivers．Once in the soil or rock，it is called groundwater．Gravity pulls groundwater through the soil in a process called percolation（渗透）．Eventually the water reaches a layer called the water table．Under this is bedrock through which water cannot percolate．

As water percolates downward，it dissolves organic matter and minerals from the soil and carries them to deeper layers．This causes a serious problem because plants require these nutrients for growth.

Soil pH

Soil can be acidic．neutral．or basic．The pH of the soil is determined by the nature of the rock

from which it was formed．and by the nature of t}le plants that grow and rot in it．

The acidity of rain and snow can lower the pH of the groundwater that enters the soil．By burning fossil fuels such as coal，oil and gasoline，humans have been contributing to higher levels of acidity in many soils．When fossil fuels are burned．gases are released into the air and then fall back to earth as acid rain．Acid soil increases出e problem of carrying nutrients to lower soil levels．As nutrients are removed，soil is less fertile．Plants grow more slowly in acidic soil，and also become easily attacked by diseases．

67．The layer of soil that provides necessary nutrients for plant growth is called．

A．1itter    B．topsoil    C．humus D．subsoil

68．According to the text．which of the following is NOT true?

A．Soil forms from weathered rock on the earth surface．

B．The deeper layer of soil is darker in colour than t}le surface soil．

C．Air pollution is partially responsible for acid soil．

D．Groundwater tends to carry away nutrients for plant growth．

69．We can infer from the passage that the water table lies       ．

A．between the topsoil layer and the subsoil layer

B．in the subsoil layer above bedrock

C．between the subsoil layer and bedrock

D．in the bedrock layer beneath the subsoil

70．The underlined word “dissolve” is used to express the idea that organic matter and minerals from soil are          ．

A．rushed away into the river

B．cleaned and purified by water

C．destroyed and carried away by water

D．mixed with water and become part of it

Have you ever noticed the colour of the water in a river or stream after a heavy rainfall? What do you think caused this change in colour? It is soil that has been washed into the river from the riverbank or from t}le nearby fields．

Components of Soft

    Soil is made up of a number of layers(层)，each having its own distinctive colour and texture．The upper layer is known as the litter．It acts like a blanket．limiting temperature changes and reducing water loss．The topsoil layer is made up of small particles of rock mixed with rotten plant and animal matter called humus(腐殖质)，which is black and gives the topsoil its dark colour．This layer is usually rich in nutrients，oxygen，and water．Below the topsoil is the subsoil，a layer that contains more stones mixed with only small amounts of organic matter．This layer is lighter in colour because of the lack of humus．Beneath the soil lies a layer of bedrock．

    Soil forms from the bottom up．Over time bedrock is attacked by rain, wind，frost, and snow．It is gradually broken down into smaller particles in a process called weathering．Plants begin to grow，and rotten materials enrich the topsoil．Most of the soil in Eastern Canada．for example．Was formed from weathered rock that was exposed when the ice disappeared l2．000 years ag0．

Water Beneath the Soil

    Surface water collects and flows above the ground in lakes．ponds．and rivers．Once in the soil or rock，it is called groundwater．Gravity pulls groundwater through the soil in a process called percolation(渗透)．Eventually the water reaches a layer called the water table．Under this is bedrock through which water cannot percolate．

    As water percolates downward，it dissolves organic matter and minerals from the soil and carries them to deeper layers．This causes a serious problem because plants require these nutrients for growth.

Soil pH

    Soil can be acidic．neutral．or basic．The pH of the soil is determined by the nature of the rock

from which it was formed．and by the nature of t}le plants that grow and rot in it．

    The acidity of rain and snow can lower the pH of the groundwater that enters the soil．By burning fossil fuels such as coal，oil and gasoline，humans have been contributing to higher levels of acidity in many soils．When fossil fuels are burned．gases are released into the air and then fall back to earth as acid rain．Acid soil increases出e problem of carrying nutrients to lower soil levels．As nutrients are removed，soil is less fertile．Plants grow more slowly in acidic soil，and also become easily attacked by diseases．

67．The layer of soil that provides necessary nutrients for plant growth is called．

    A．1itter    B．topsoil    C．humus D．subsoil

68．According to the text．which of the following is NOT true?

    A．Soil forms from weathered rock on the earth surface．

  B．The deeper layer of soil is darker in colour than t}le surface soil．

  C．Air pollution is partially responsible for acid soil．

    D．Groundwater tends to carry away nutrients for plant growth．

69．We can infer from the passage that the water table lies       ．

A．between the topsoil layer and the subsoil layer

B．in the subsoil layer above bedrock

       C．between the subsoil layer and bedrock

       D．in the bedrock layer beneath the subsoil

70．The underlined word “dissolve” is used to express the idea that organic matter and minerals from soil are          ． 

    A．rushed away into the river

    B．cleaned and purified by water

    C．destroyed and carried away by water

    D．mixed with water and become part of it

Children at a school in Italy have today begun an experiment to replace all their books with personal computers. The pupils involved will each be given a special laptop that contains their entire courses.
Until today, the Don Milani di Rivoli elementary school in central Turin was like any other. Children turned up, got out their books and pens and began the process of learning. But now, in what's being described as a unique experiment, 60 fifth-grade pupils and a number of third-graders, will start using computers only.
The mini-laptops, which run Windows software, all have a full curriculum programmed into them. The pupils will use the computers to do all their reading and writing. Security systems within the laptops mean the children's access to the Internet is strictly controlled. The machines weigh less than a kilogram, can be dropped from a height of 1.5 metres and are waterproof.
Instead of spending 700 dollars a year on books, the laptops, built by the Italian company Olidata, cost less than 400 dollars. One of the teachers involved in the scheme says that, for the first time, schools will be able to verify in a scientific way how a computer alone can improve the learning process. The experiment, which has the backing of parents, is due to last a year.
In other countries, such a programme is also being carried out. Venezuela is ordering one million low cost laptops for its school children. The machines will be based on the Intel Classmate laptop that has been designed for school children. Many see the deal as a blow for the One Laptop Per Child organization that has also been introducing its child- friendly machine to developing nations.
【小题1】 Which of the following is TRUE about the mini-laptop?

Children at a school in Italy have today begun an experiment to replace all their books with personal computers. The pupils involved will each be given a special laptop that contains their entire courses.

Until today, the Don Milani di Rivoli elementary school in central Turin was like any other. Children turned up, got out their books and pens and began the process of learning. But now, in what's being described as a unique experiment, 60 fifth-grade pupils and a number of third-graders, will start using computers only.

The mini-laptops, which run Windows software, all have a full curriculum programmed into them. The pupils will use the computers to do all their reading and writing. Security systems within the laptops mean the children's access to the Internet is strictly controlled. The machines weigh less than a kilogram, can be dropped from a height of 1.5 metres and are waterproof.

Instead of spending 700 dollars a year on books, the laptops, built by the Italian company Olidata, cost less than 400 dollars. One of the teachers involved in the scheme says that, for the first time, schools will be able to verify in a scientific way how a computer alone can improve the learning process. The experiment, which has the backing of parents, is due to last a year.

In other countries, such a programme is also being carried out. Venezuela is ordering one million low cost laptops for its school children. The machines will be based on the Intel Classmate laptop that has been designed for school children. Many see the deal as a blow for the One Laptop Per Child organization that has also been introducing its child- friendly machine to developing nations.

Which of the following is TRUE about the mini-laptop?

A. It is heavy for pupils to carry.         B. It can't be damaged by water.

C. It is one and a half meters high.              D. It is easily broken or damaged.

The pupils use the laptop to ____ in class.

A. learn their lessons as an aid

B. have a course named computer studies

C. surf the Internet mainly to find information

D. do what they used to do with books and pens

How much money can a pupil save by using the mini-laptop to replace all the books in a year?

A. Less than 400 dollars.                            B. More than 400 dollars.

C. More than 300 dollars.                   D. Less than 300 dollars.

Which of the following about the experiment is TRUE?

A. It has been carried out for over one year.

B. It has already turned out to be a success.

C. The pupils' parents are against it in fact.

D. The pupils' parents are supportive to it.

 A new study（研究）warns that about thirty percent of the world’s people may not have enough water by the year 2025.

     A private American organization called Population Action International did the new study. It says more than three hundred thirty-five million people lack enough water now. The people live in twenty-eight countries. Most of the countries are in Africa or the Middle East.

     Population Action International researcher Robert Engelman says by the year 2025, about three thousand million people may lack water. At least 18 more countries are expected to have severe water problems. The demand for water keeps increasing. Yet, the amount of water on earth stays the same.

Mr. Engelman says the population in countries that lack water is growing faster than in other parts of the world. He says population growth in these countries will continue to increase.

The report says lack of water in the future may result in several problems. It may increase health problems. Lack of water often means drinking water is not safe. Mr. Engelman says there are problems all over the world because of diseases, such as cholera, which is carried in water. Lack of water may also result in more international conflict. Countries may have to compete for water in the future. Some countries now get sixty percent of their fresh water from other countries. This is true of Egypt, the Netherlands, Cambodia, Syria, Sudan and Iraq. And the report says lack of water would affect the ability of developing to improve their economies. This is because new industries often need a large amount of water when they are beginning.

    The Population Action International study gives several solutions to the water problem. One way, it says, is to find ways to use water for more than one purpose. Another way is to teach people to be careful not to waste water. A third way is to use less water of agriculture.

    The report also says long-term solutions to the water problem must include controls on population growth, It says countries can't provide clean water unless they slow population growth by limiting the number of children people have.

1. According to the writer’s opinion, the first serious problem caused by lack of water is ______.

   A. health problem  B. war  C. economy  D. industry

2.Robert Engelman may be _______.

   A. an Englishman  B. an American  C. a Japanese  D. an Australian

3.Which of the following is NOT the way to solve the water problem?

   A. To control population growth

   B. To teach people not to waste water.

   C. To find ways to use water for only one purpose.

   D. To use less water of agriculture.

4. What is the main idea of the passage?

    A. How to get more water in the future.     B. Problems caused by water

C. The Lack of water                    D. A new study of water