Mountain climbers around the world dream     1     going up Qomolangma, the highest mountain in the world.     2     many people who have climbed the mountain have left waste material that is harming the environment.

A team of Americans is planning the largest clean-up effort ever on Qomolangma. They will make the     3    (risk) trip of all time up the mountain next month.

The team of eight Americans     4    (guide) by more than twenty Sherpas of Nepal (尼泊尔夏尔巴人). Their goal is     5    (remove) all the rubbish they see. They will spend two months cleaning up the mountain by gathering all kinds of rubbish, among     6     disposable products are a major concern. So the clean-up team will take along     7    (new) developed equipment to collect and treat disposable products. They are expected to remove at least three     8    (ton) of rubbish in large bags.

Team leader Robert Hoffman is making his     9    (four) trip up the mountain. He says he hopes to bring Qomolangma to the condition it was in before the first climb     10    (complete) successfully fifty years ago.

3 . Last night’s meteor(流星) shower left many people in the community dissatisfied and demanding answers. According to Gabe Rothsclild, Emerald Valley’s mayor, people gathered in the suburbs of the city, carrying heavy telescopes, expecting to watch the brightly burning meteors passing through the sky. What they found instead was a sky so brightened by the city’s lights that it darkened the light of the meteors passing overhead.

“My family was so frustrated,” admitted town resident Duane Cosby, “We wanted to make this an unforgettable family outing, but it turned out to be a huge disappointment.”

Astronomers—scientists who study stars and planets—have been complaining about this problem for decades. They say that light pollution prevents them from seeing objects in the sky that they could see quite easily in the past. They call on people and the government to take measures to fight against it.

There is yet a population besides professional and amateur star observers that suffers even more from light pollution. This population consists of birds, bats frogs, snakes, etc. For example, outdoor lighting severely affects migrating birds. According to the International Dark-Sky Association. “100 million birds a year throughout North America die in crashes with lighted buildings and towers.”

Countless more animals casualties result from the use of artificial lighting. Clearly, people enjoy the benefits of lighting their evenings, but some scientists think it can be harmful for humans, too. They worry that exposure to light while sleeping can increase person’s chances of getting cancer.

Emerald Valley is only one community that is becoming aware of the negative effects of high pollution. For years, Flagstaff, Arizona, has enforced lighting regulations in its city in order to assist astronomers at the Lowell Observatory. Similar efforts have been made worldwide, and a movement is underway to remind us to turn off lights when we are not using them, so that other creatures can share the night.

4 . If humans were truly at home under the light of the moon and stars, we would go in darkness happily, the midnight world as visible to us as it is to the vast number of nocturnal(夜间活动的) species on this planet. Instead, we are diurnal(白天活动的) creatures, which explains what we’ve done to the night: We've engineered it to receive us by filling it with light.

The benefits of this kind of engineering come with consequences—light pollution. Light pollution is largely the result of bad lighting design, which washes out the darkness of night and completely changes the light levels and rhythms to which many forms of life, including, ourselves, have adapted. Wherever human light spills into the natural world, some aspect of life is affected.

In most cities the sky looks as though it has been emptied of stars, leaving behind a vacant haze(霾) that mirrors our fear of the dark. We've grown so used to this orange haze that the original glory of an unlit night—dark enough for the planet Venus to throw shadow on Earth—is wholly beyond our experience.

We've lit up the night as if it were an unoccupied country, when nothing could be further from the truth. Among mammals alone, the number of nocturnal species is astonishing. Light is a powerful biological force, and on many species it acts as a magnet(磁铁). The effect is so powerful that scientists speak of songbirds and seabirds being ''captured'' by searchlights on land or by the light from gas flares on marine oil platforms.

Frogs living near brightly lit highways suffer nocturnal light levels that are as much as a million times brighter than normal, throwing nearly every aspect of their behavior out of joint, including their nighttime breeding choruses. Humans are no less trapped by light pollution than the frogs. Like most other creatures, we do need darkness. Darkness is as essential to our biological welfare, to our internal clockwork, as light itself.

Living in a glare of our making, we have cut ourselves off from our evolutionary and cultural heritage—the light of the stars and the rhythms of day and night. In a very real sense, light pollution causes us to lose sight of our true place in the universe, to forget the scale of our being, which is best measured against the dimensions of a deep night with the Milky Way—the edge of our galaxy—arching overhead.

5 . Blue Planet II’s latest episode (剧集) focuses on how plastic is having a devastating effect on the ocean and slowly poisoning our sea creatures. Researchers recently also found that sea creatures living in the deepest place on Earth, the Mariana Trench, have plastic in their stomachs. Indeed, the oceans are drowning in plastics.

Though it seems now that the world couldn’t possibly function without plastics, consumer plastics are a remarkably recent invention. The first plastic bags were introduced in the 1950s, the same decade that plastic packaging began gaining in popularity in the United States. This growth has happened so fast that science is still catching up with the change. Plastics pollution research, for instance, is still a very early science.

We put all these plastics into the environment and we still don’t really know what the outcomes are going to be. What we do know, though, is disturbing. Ocean plastic is estimated to kill millions of marine animals every year. Nearly 700 species, including endangered ones, are known to have been affected by it. One in three leatherback turtles, which often mistake plastic bags for jellyfish, have been found with plastic in their bellies. Ninety percent of seabirds are now eating plastics on a regular basis. By 2050, that figure is expected to rise to 100 percent.

And it’s not just wildlife that is threatened by the plastics in our seas. Humans are consuming plastics through the seafood we eat. I could understand why some people see ocean plastic as a disaster, worth mentioning in the same breath as climate change. But ocean plastic is not as complicated as climate change. There are no ocean trash deniers (否认者), at least so far. To do something about it, we don’t have to remake our planet energy system.

This is not a problem where we don’t know what the solution is. We know how to pick up garbage. We know how to recycle. We can all start by thinking twice before we use single-use plastic products. Things that may seem ordinary, like using a reusable bottle or a reusable bag — taken collectively, really do make a difference.

6 . Thanks to Earth, we have fresh air to breathe, clean water to drink and warm sunshine to enjoy. But it seems that we may have taken these things for granted and not realized that our planet is getting “sick”.     1     More than 15,000 scientists around the world have written a letter to warn about environmental challenges.

Among those environmental challenges, climate change sits at the top. Global average temperatures have risen by more than 0.5℃ since 1992.     2     It means that heat waves would last around a third longer and rainstorms would be about a third more violent if we take no action. The increase in sea levels would also be much higher. Countries like Singapore and Tokyo that are at low altitudes (海拔) may be covered by the ocean in the future.

    3     It’s getting harder to get fresh water. Ocean pollution has become serious. Since 1992, the human population has grown by 2 billion, while the populations of all other animals have dropped by nearly 30 percent.

Scientists say that we are experiencing the sixth mass extinction (物种大灭绝) in history. More than two-thirds of the world’s wildlife could be gone by the end of the decade if action isn’t taken soon.     4    

However, we have made some progress by making the hole in the ozone (臭氧) layer smaller. That’s because we gradually stopped using chemicals that can break down ozone, a gas that protects Earth.

    5    

7 . Main Types of Water Pollution

When we think of Earth’s water resources, we think of huge oceans, lakes, and rivers.     1     The most obvious type of water pollution affects surface water. For example, a spill from an oil tanker creates an oil layer that can affect a vast area of an ocean.

    2     A great deal of water is held in underground rock structures known as aquifers(含水层). Water stored underground in aquifers is known as groundwater. Aquifers feed our rivers and supply much of our drinking water. They can also become polluted, for example, when weedkillers used in people’s gardens drain into the ground.

Surface water and groundwater are the two types of water resources that pollution affects.     3     If pollution comes from a single location, such as a pipe attached to a factory, it is known as point source pollution.     4     A great deal of water pollution happens not from one single source but from many different sources. This is called nonpoint source pollution.

Sometimes pollution that enters the environment in one place has an effect hundreds or even thousands of miles away.     5     One example is the way radioactive waste travels through the oceans from unclear reprocessing plants in England and France to nearby countries such as Ireland and Norway.