We sometimes call the lion "the king of the forest" , because it is stronger and more dangerous than other animals. It can 1 faster than many animals and hunt the best. It is the highest animal in the 2 food chain.
In the sea, the shark is one of the animals at the top of the food chain. It can swim faster than 3 other sea animals, and it can use its big teeth to eat them.
What is at the top of the world's food chain？People are! We are not the biggest or fastest, but we are the 4.We could not run faster than cheetahs (猎豹), so we 5 cars and now we can move the fastest. We could not fight better than lions, so we invented guns. Now we can hunt the best.
People's inventions are clever, but they can be 6 ， too. For example, people built 7 ， and now they make the air and rivers dirty. This can make terrible changes. Dirty rivers kill fish.8 bears cannot eat the fish. If we kill one part of the food chain, other parts will also die. Remember that we are a part of the food chain, 9 we are in danger, too! If we protect animals, we are protecting 10! We could and we should do something for the world!
|
Cities |
Population (million) |
Persons per room |
Telephones per 100 people |
children in middle school |
|
Tokyo |
28.7 |
0.9 |
44 |
97% |
|
Seoul |
15.8 |
2.0 |
22 |
90% |
|
London |
11.0 |
0.6 |
50 |
58% |
|
Moscow |
13.2 |
1.3 |
39 |
100% |
Hundreds of years ago, life was harder than it is today. People didn't have modern machines. There was no modern medicine, either.
Life today has brought new problems. One of the biggest is pollution. Water pollution has made our rivers and lakes dirty. It kills our fish and pollutes our drinking water. Noise pollution makes us talk louder and become angry more easily. Air pollution is the most serious kind of pollution to all living things in the world.
Cars, planes and factories all pollute our air every day. Sometimes the polluted air is so thick that it is like a quilt (被状物) over a city. This kind of quilt is called smog.
Many countries are making rules to fight pollution. Factories must now clean their water before it is thrown away, and they mustn't let dirty smoke go into the air.
We need to do many other things. We can put waste things in the dustbin and not throw them on the ground. We can go to work by bus or with our friends in the same car. If there are fewer people driving, there will be less pollution.
Rules are not enough. Every person must help to fight pollution.
A very important world problem is the growing population on the earth. The population of the world today is more than 6, 500, 000,000. That is a great number and we know it quite well. The important thing is not how large the population of the world is now, but is the rate of the growth— it is about 1.63 percent every year.
Every second, four babies are born in the world. Another baby! Another baby! Another baby! Another baby! You can not speak quickly enough to keep up with the birth rate. The population is growing larger and larger. In one day, people have to find food for over 350, 000 mouths.
This great growing population will make a big problem—there have been over 7 billion people on the earth. So this is one of the biggest problems which you are going to see in your life.
Counting Our People
From Nov. 1 to Dec. 10, 2020, if someone knocks at your door and wants to ask you some questions, don't be afraid. They are working on the seventh national population census. They will ask each family about their name, gender, age, education, and employment (职业).
China has a census about every 10 years. The first one was done in 1953. At that time, there were about 600 million people in China. It was about 1.37 billion in 2010, according to the National Bureau of Statistics (NBS国家统计局).
For this year's census, China will send 7 million staff to visit families across the country. All residents (居民) of China will be included in the census. But Chinese citizens who have settled (定居) abroad and foreign citizens who are staying in China on either business or tourist visas (签证) will not be counted.
"The census is very important for every citizen," said Ning Jizhe, director of the NBS. "It will help improve infrastructure (基础建设) and public services." For example, if census results show that there are many children living in a particular area, the government will know that it should build more schools there.
Scientists can also learn more about population growth from the census. In some years, the population grows faster than in others. Even in the same year, population growth is different in different places. Scientists can use the information to figure out what causes growth in certain years and places.
