In the time it takes you to read this sentence, the population of the world will have grown by ten people. That
may not sound much, but it is 9,000 people in an hour, 1.5 million a week, or 79 million a year. That is the same
as adding most of the population of Germany to the world every year.
    Most of these new people were born in developing countries. These countries are found in much of Africa,
South America and parts of Asia. In the developed countries of Europe and North America, the population is
growing very slowly. This is because women in these countries have, on average, only one or two children. In
the developing countries, many women have five or more children. In 1950, around one quarter of the world's
population lived in the developed countries. By 2050, these countries will be home to only around one tenth of
the world's people.
     In the developing countries, more than one billion people already live below the poverty (貧困) line. These
people do not have enough food to eat and they live in poor housing; children get little or no time at school and
people suffer (遭受痛苦) from many kinds of diseases.
    At the beginning of the 21st century, the world's population was around six billion people. The UN has said
that the world's population will level off at 12.5 billion people by the year 2100. Other groups think the world's
population will continue to grow, reaching 14 billion people before it becomes stable (穩(wěn)定的), or even falls.
1. How many people are added to the world's population an hour? 
   __________________________________________________
2. Developing countries can be found in what areas of the world?
   __________________________________________________
3. In 1950, what percentage (百分率) of the world's population lived in developing countries?
   __________________________________________________ 
4. What are examples that show people are living below the poverty line?
   __________________________________________________
5. There will be twelve and a half billion people on the earth in 2100 according to the UN, won't there?
                                                                                            

    Are you carrying too much on your back to school? I'm sure lots of your age will say "Yes". Not only the
students in China have this problem, but children in the United States also have heavy school bags.
    Doctors are starting to worry about that younger and younger students are having problems as a result of
school bags being too heavy for them. 
    "It's hard for me to go upstairs with my bag because it's so heavy," said Rich Hammond, an 11-year-old
student in the US.
    Rich is among students who have common school bags with two straps to carry them, but many other
choose rolling (轉(zhuǎn)動的) bags.
    But even with rolling bags, getting up stairs and houses is still a problem for children. Many of them have
hurt backs and necks because of the heavy school bags.
    But how much is too much? Doctors say students should carry no more than 10% to 15% of their own
body weight.
    Scott Bautch, a black doctor, said children under Grade 4 should stay with 10%. But it is also important that
older children don't stay with over 15%, because their bodies are still growing. "Children are losing their balance
and falling down with their school bags," he said.
    Parents and teachers are starting to tell children to only take home library books that they will be reading at
night. Some teachers are using pieces of paper or thin workbooks for students to take home.
    One of the best answer is , as some children said ,to have no homework at all.