2 . The world’s forests may hold more secrets than previously thought: a new global estimate of tree biodiversity suggests that there are about 9,200 tree species remaining undocumented. Most are likely in the tropics, according to the new research.

The new research drew on the efforts of hundreds of contributors, who have categorized trees in two huge data sets: One, the Global Forest Biodiversity Initiative, records every species found in extensively documented forest plots worldwide. The other, TREECHANGE, puts together sightings of individual species. Together they suggest there are approximately 64,100 recorded tree species on the planet — up from previous estimates of around 60,000.

The researchers reached their estimate of an additional 9,200 yet undocumented species on the basis of the number of rare ones already in the databases. Most unknown species are likely to be defined as rare, found in limited numbers in small geographical areas, says the quantitative forest ecologist Jingjing Liang. The team’s result is “a rather conservative estimate,” Liang says, “because scientists know less about the preponderance of uncommon trees in places such as the Amazon, where out-of-the-way spots could host pockets of unusual species found nowhere else.” “If we can focus the resources on those rain forests in the Amazon,” Liang adds, “then we would be able to estimate it with higher confidence.”

Silman, a conservation biologist, who was not involved in the new study agrees that the study result is likely an underestimate. His and his colleagues’ local surveys suggest there are at least 3,000 and possibly more than 6,000 unknown tree species in the Amazon basin alone. Tree species often get grouped together based on appearance, he notes, so new genetic analysis techniques will likely lead to the discovery of even more biodiversity. Sliman wonders how many species will go extinct before scientists describe them. “How many are already known to native peoples in the Amazon — or were known to peoples or cultures who have themselves been made extinct through colonization, disease, or absorption? How many “species” already have dried samples sitting in a cabinet?” he says.

Searching for the new species will inform not only conservation but the basic evolutionary science of how and why species diversify and die out, Silman says. “Just the fact that there are thousands of species of something as common as trees out there that are still left to be discovered,” he adds, “I find pretty inspirational.”

The environment pollution is more and more seriously today. We have no clean water to drink it because of water pollution. And when trees cut down, some animals disappear. There was more and more dirty smoke in the air. People’s health has been greatly affecting by air, noise and water pollution. Many people have died of disease caused by pollution. In order to live the better life, it’s time for us to protect our world.

Firstly, we shouldn’t throw away rubbish everywhere. And we should recycle, reduce and reuse things, what saves money and reduces pollution. Use things so long as possible. Don’t use plastic bags. Besides, we must plant more trees and stop people cut them down. We hope our world will be more and more beautiful.

4 . Hundreds of years ago, life was harder than it is today. People didn't have modern machines.

Life today has brought new problems. One of the biggest problems 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 over a city. This kind of quilt is called smog.

Many countries are making rules to fight against 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 do 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 against pollution.

7 . There are many things that we can do in our own ways which will help save the environment. What are some of these ways to save the environment? Let’s take a look at a list of them.

There won’t be enough water before we need to fight for clean and fresh water. That is why saving water and preventing water pollution becomes very important. Keep simple things in mind like turning off the tap when you are brushing teeth. Don’t often take a shower. Don’t pour oil into the drains. Don’t throw rubbish into the river.

Save paper to save trees. Make sure that you use both sides of paper before throwing it away. If you can, try not to use paper as possible as you can and do not forget to recycle paper. Also, using cloth bags instead of paper bags can save much Paper. This is one of the best ways to save our environment.

Recycling is important. It makes sure that the environment is not more polluted. Recycling does not simply include recycling paper, but things like plastic, metal and office supplies like pens, ink and more. This makes sure that they are changed into material that is reusable and also puts less pressure on the environment.

What are the ways to save energy? Turn off the lights and computers before you leave. Use cold water instead of hot water to wash clothes, use the stairs instead of the lift and keep the air conditioner on moderate setting (设置) to save energy.

In a word, try our best to do something to save our environment, and we will do something helpful to save ourselves.

9 . Earthquakes are something that people fear. There are some places that have few or no earthquakes. Most places in the world, however, have them regularly (有规律的). Countries that have a lot of earthquakes are usually quite mountainous (多山的).

The earthquake which was talked about most in the United States was in San Francisco in 1906. Over 700 people died in it. The strongest one in North America was in 1964. It happened in Alaska.

Strong earthquakes are not always the ones that kill the most people. In 1755, one of the strongest earthquakes ever recorded was felt in Portugal. Around 2,000 people died.

In 1923, a very strong earthquake hit the Tokyo, Yokohama area of Japan. A hundred and forty thousand people died. Most of them died in fires which followed the earthquake.

One of the worst earthquakes ever was in China in 2008. It killed a large number of people. The worst earthquake ever reported was also in China, in which 400,000 people were killed or injured. This earthquake happened in 1556.

Earthquakes worry people a lot. The reason is that we often do not know when they are coming. People can not prepare for earthquakes.

A big storm destroyed two villages in South Africa on last Friday, causing 4 death. Over 200 people became homeless as a result of the storm. A farmer said the storm began early in the morning and last one hour. He said, “I was cooking in the kitchen with my wife and children while we heard a loud noise. A few minutes late, our house fell down. I managed to climb out, but much to my shocking, one of my boys were missing. I quickly went back inside and found them safe but frightened.” Soldiers came to rescue those burying under the ruins, and the government provided food, clothes, and shelters for homeless.