1 . Database maintenance (数据库维护) is an activity designed to keep a database running smoothly. A number of different systems can be used to build and maintain databases. Databases are used to maintain a library of information in a well-organized, accessible format (格 式).They usually are not static (静态的),because changes are constantly being made as material is added, removed, and moved around. Over time, this can cause the database to start to go wrong. Database maintenance is used to keep the database clean and well-organized so that it will not lose functionality.

One important aspect of maintaining a database is simply backing up the data so that, if anything happens, there will be another copy available. Some database systems actually do this automatically and then send the backup to another location every day, every week, or within any other set period of time. Backups are usually not enough, however.

Database maintenance includes checking for signs of corruption in the database, looking for problem areas, and checking for any detail in the database that might signal a problem. The goal is to keep the database operating smoothly for users, so that ideally they never need to think about maintenance issues. A database that is not maintained can become slow, and people may start to experience problems when trying to access records.

The maintenance of databases is generally performed by people who are comfortable and familiar with the database system and the details of the particular database, although some maintenance tasks can be performed by people who do not have experience. Numerous textbooks are available with information about database management, including how to maintain databases properly. It is also possible to take courses to learn about different database systems and how to care for databases. People can also earn certifications in specific systems which indicate a high level of competence.

1. What can we know about databases?

A．They are always well organized.	B．They are often changeable.
C．They mainly serve the library.	D．They can organize news.

2. What does the underlined part “do this" in paragraph 2 refer to?

A．Maintain a database.	B．Send a backup.
C．Correct mistakes.	D．Back up data.

3. What is the aim of database maintenance?

A．To look for signs of breaking down.	B．To check for any detail.
C．To make database run smoothly.	D．To ensure the safety of users.

4. What is the text mainly about?

A．What database maintenance is.

B．How people keep database operating smoothly.

C．How people finish maintenance tasks well.

D．Why database maintenance is important.

2 . In the struggle to survive the ever hotter deserts of California, there are winners and losers. Among the losers are desert birds, whose populations have fallen among the heat stress of climate change. The winners, it turns out, are small burrowing mammals（穴居哺乳动物）, which take refuge from the sun underground. Researchers noted that the stable mammals populations formed a striking contrast to the extremely bad condition of birds.

But why? Birds had a higher evaporative（蒸发）heat loss. Birds were more exposed to the effects of warming, so they had higher energy costs to maintain their body temperature. However, mammals were able to reduce their body temperature by using burrows during the day.

Temperatures have risen about 4 degrees Fahrenheit on average across the area studied, but the heat affects birds and small mammals differently. As part of the study, scientists modeled each species' body temperature and cooling needs under different desert conditions. To calculate that, they measured the conductivity（传导率）of the animals' fur or feathers, and used information on their heat reducing behaviors.

The models showed that in the fight against climate change, there was not a level playing field for furred and feathered desert animals. Cooling costs—or the resources needed to maintain stable body temperature—were about 3. 3 times higher for birds than they were for small mammals, the study reported.

Small mammals have shown this remarkable stability. It's really quite interesting that, in the same region, with the same level of climate change, these two species have responded very differently to the changes taking place. Insights into the status of different species can help scientists take steps to protect them, such as increasing fire prevention in high desert areas, and enhancing water sources in those areas. The study also demonstrates that climate change is already reshaping the California desert

1. Why can desert burrowing mammals survive better than desert birds?

A．Burrowing mammals prefer to live in deserts.

B．Burrowing mammals eat less during the day.

C．Burrowing mammals' caves are natural shelters.

D．Burrowing mammals live in the same community.

2. What can we learn from the third paragraph?

A．Birds and small mammals respond differently to climate changes.

B．Birds in the desert were defeated by climate changes.

C．Animals living underground have higher cooling costs.

D．Temperature rise affects the burrowing mammals little.

3. What is the possible meaning of the new finding?

A．Burrowing mammals may help birds during the day.

B．Governments will improve water quality.

C．Man will reshape the deserts to save themselves.

D．Scientists can save species with scientific means.

4. What do we know from the text?

A．It's time to change the deserts into green fields.

B．Desert birds are more likely to survive in deserts.

C．Burrowing mammals' habitat needs improving greatly.

D．Burrowing mammals survive climate change underground.

3 . The best science fiction books of 2021

We take a look at the most exciting new science-fiction books of 2021. No matter what kind of science fiction fan you are, we're sure you'll find something to add to your reading list.

The Saints of Salvation

By Peter F. Hamilton

The Olyix have laid siege（围攻）to Earth, harvesting people for their god. Cities are ru¬ined by their weapons and millions have either fled to seek refuge in space or are fighting a war that seems unwinnable. As Earth's defeat draws ever closer, a team are sent to enter the Olyix's air-ship secretly. Their plan? This is the final science fiction in Peter F. Hamilton's extremely surprising series The Salvation Sequence.

A Desolation Called Peace

By Arkady Martine

This impressive sequel（续集）to Arkady Martinets Hugo Award-winning science fiction book sees the Teixcalaanli Empire facing an alien threat which could bring about its complete destruction. Fleet captain Nine Hibiscus sends a person to negotiate with the mysterious invaders...

Jack Four

By Neal Asher

Jack Four-one of twenty human clones-has been created to be sold. His purchasers are the aliens and they only want him for their experimentation program. But there is something different about Jack. No clone should possess the knowledge that's been loaded into his mind.

Rabbits

By Terry Miles

Rabbits is a secret, dangerous and sometimes deadly underground game. The rewards for winning are unclear, but there are rumors of money or it might unlock the universe's greatest secrets. Everyone knows that the deeper you get, the more deadly the game becomes-and the body count is rising. Since the game first started, ten rounds have taken place. The eleventh round is about to begin, and what happens in the game, stays in the game...

1. What can we know aboutThe Saints of Salvation?

A．It's about the war among people on earth.

B．The Olyix are defeated in the end.

C．It belongs toThe Salvation Sequence.

D．It's the last novel of Peter F. Hamilton.

2. What does Nine Hibiscus do to save Teixcalaanli Empire?

A．He gives the alien a complete destruction.

B．He lets someone negotiate with the alien.

C．He fights against the alien bravely.

D．He makes the alien face a threat.

3. Where can the text be found?

A．In a book recommendation.	B．In an art magazine.
C．In a biography.	D．In a novel