【推荐3】How to Build a Natural Swimming Pool

Whether you like to practice your dolphin dives or lounge away the day on a raft, swimming is one of summer's perfect pleasures. With a minimum of materials and without so many chemicals, you can create a cooling summer retreat in your back yard.

Though fairly common in Europe, natural swimming pools, are in their early stage in the United States. You can ask most American swimming-pool contractors to build a backyard pool.     1    . The list may include rebar（钢筋）, gunite(水泥砂浆), fiberglass, chlorine and an energy-sapping filtration system.

But in recent years, a few builders and a growing number of homeowners have learned how to build pools.     2    . They've found it's possible to construct pools that are more about building with nature and blending into the natural landscape. Natural swimming pools use gravel stone and clay in place of concrete or fiberglass, and aquatic plants instead of harmful chemicals and complicated mechanical filtering systems.     3    . They also support beneficial bacteria that consume debris and potentially harmful organisms, and give habitat to frogs, dragonflies and other water life.

    4    . A natural pool can he constructed for as little as $2,000 if you do it yourself, while conventional pools can cost tens of thousands of dollars.

Natural swimming pools require no harmful chemicals, are fairly low-tech.     5    . You won’t have to drain the pool each autumn. Except for topping it off now and then, you'll fill the pool only once.

A．The plants enrich the pool with oxygen.

B．Chances are that they will roll out a long list of goods.

C．You can make your pool as shallow or as deep as you want.

D．And once established, they call for only a bit of management.

E．It is the most ecological and economic way to build a conventional pool.

F．They don’t rely on a mass of manufactured materials and chemical additives.

G．The result is a beautiful and ecologically system that is relatively inexpensive to construct.

【推荐2】Magnetic fields are promising to be a useful tool in the hunt for human settlements that have been lost to the sea off the coast of the UK. An upcoming project is set to use magnetometry (磁力测定) data to seek Doggerland, the flooded land that connected Britain to mainland Europe until the end of the Ice Age, but there’s hope that this technique could be used to find long-lost civilizations all over the world.

The study comes from the University of Bradford in the UK. Their plan is to closely look at magnetometry data gathered from a portion of the North Sea and attempt to identify any strange anomalies (异常) that could suggest the presence of archaeological structures.

The team is especially keen to use these techniques to look for traces of human activities beneath the North Sea since it’s thought to have been home to some of the largest prehistoric settlements in Europe. Before it was flooded over 8,000 years ago. Doggerland was a rich and diverse habitat that likely attracted prehistoric humans and others. Despite its potential that lays beneath the North Sea, we know relatively little about the culture that once was developed here.

“As the area we are studying used to be above sea level, there’s a small chance this analysis could even reveal evidence for hunter-gatherer activity. That would be the most important part.” Ben Urmston, PhD student at the University of Bradford, said in a statement. “We might also discover the presence of middens, which are rubbish dumps that consist of animal bones, shells and other biological material. that can tell us a lot about how people lived.”

Remarkably little of the world’s oceans have been explored, let alone for the purposes of archaeology. Nevertheless, advances in technology are continuing to show that the coastlines are hiding countless traces of ancient human activities, even evidence of long-lost civilizations.

Thanks to projects like the one at the University of Bradford, as well as many others, the future of marine archaeology is looking promising. Nevertheless, we have to be patient. Just don’t expect to stumble across the sunken city of Atlantis anytime soon.

1. Why is magnetometry data used in this project?

A．To trace the ice movement.	B．To measure Doggerland.
C．To find a lost ancient land.	D．To explore the history of Britain.

2. What do we know about Doggerland over 8,000 years ago?

A．Its civilization is little known to us.	B．It was a place that was often flooded.
C．It was a deserted island with few people.	D．Its location has not yet been confirmed.

3. What is Ben Urmston’s attitude toward this analysis?

A．Uncaring.

B．Subjective.

C．Shocked.

D．Favourable.

4. What do the underlined words ”stumble across“in the last paragraph mean?

A．Display.

B．Assess.

C．Restore.

D．Discover.

【推荐3】The second experiment on how to grow crops on mimic (模拟的) Mars and Moon soil has given a surprising outcome (成果). The Wageningen UR researchers use the Mars and Moon soil provided by NASA. Mimic Mars soil comes from a volcano in Hawaii and the mimic Moon soil from an Arizonian desert. As a result of what the researchers of Wageningen University in the Netherlands learned from their first experiment, which was a failure, they were finally able to grow ten different crops. The tomatoes, peas, turnip, and cabbages have been harvested (收割). The goal of the experiments is to provide the way of growing crops on Mars or on the Moon in order to feed the first settlers.

A few improvements have been made since the first experiment, though it isn’t a success. Professor Wamelink says, “We used plates instead of small pots and added organic material (fresh cut grass) to the Mars and Moon soil. This is what we didn’t do in the first experiment. This solved the problem we had with watering in the first experiment and also added manure (肥料) to the soil.” In the first Moon soil experiment most plants died; in the next round they flourished (茂盛), and the researchers could harvest from some species. It can be regarded as a triumph when it is compared with the first one.

Although the Wageningen researchers harvested several crops, they did not eat them. Wamelink says, “The soil contains heavy metals. If heavy metals find their way into the crops, they will make them poisonous for human beings. Then further research on this is necessary because they need to make sure the final harvest must be harmless to human beings. The experiment should start in April next year with the growth of new crops including potatoes and beans.”

The soil experiment began in April and the final harvest took place in October. Plants were grown in a glass house under certain temperature and light conditions and under the earth atmosphere. “This is because we expect that first crop growth on Mars and the Moon will take place in underground rooms to protect the plants from the bad environment,” says Wamelink.

1. Why were the scientists able to grow ten different crops?

A．Because they had the experience from last failure.

B．Because they experimented a number of times.

C．Because they worked harder this time than last time.

D．Because they got a lot of help from other countries.

2. What is the difference between the first and the second experiment according to the passage?

A．The grass covering the crops.

B．Watering the crops regularly.

C．Replacing different kinds of plants.

D．The use of plates and organic material.

3. What will the researchers probably center on in the following experiment?

A．How to plant crops in underground rooms.

B．Whether these crops can be eaten by human beings.

C．How to plant more and more crops on Mars and the Moon.

D．Whether tomatoes and beans can grow on Mars and the Moon.

4. Which of the following would be the best title for this passage?

A．Experiments Prove Crops can Grow on Mars

B．A Great Science Achievement has been Made

C．Crops Harvested on Mimic Mars and Moon Soil

D．First Settlers can Eat Crops Grown on the Moon