Rivers are the veins of the Earth, transporting the water and nutrients (营养物) needed to support the planet’s ecosystems, including human life. While many nutrients are essential to the survival of life, there is one element transported by water in rivers that holds the key to life and to the future of our planet — carbon.
Carbon is everywhere and understanding the way it moves and is either released or stored by the Earth system is a complex science in itself. Carbon starts its journey downstream when natural acid rain, which contains carbon dioxide from the atmosphere, melts minerals in rocks. This helps transform carbon dioxide to bicarbonate (碳酸氢盐) in the water that then flows in our rivers. This is a very long process, which is one of the main ways carbon dioxide is removed from the atmosphere. Carbon is transported by rivers to oceans and once that carbon reaches the ocean, it is stored naturally in deep sea sediments (沉淀物) for millions of years.
As carbon travels down a river, different processes may impact whether it continues to flow downstream or whether it is released into the atmosphere. For example, human engineering, like extensive dam construction, will result in dramatic changes to how water and sediments travel down the river. Some carbon that fails to reach the sea may return to the atmosphere in some way, which causes more warming.
Earth’s climate is closely related to the carbon cycle. We all know about the essential role of plants in consuming carbon dioxide, but do we know enough about rivers? Changing the chemistry and the course of rivers may have significant impacts on how they transport carbon. Remember: wherever we live, we all live downstream.
1.Where is the carbon in rivers originally from?
A.The atmosphere. B.The rocks.
C.The acid rain. D.The upstream areas.
2.Why is human engineering mentioned in Paragraph 3?
A.To show how important to life carbon is.
B.To explain how necessary it is to build dams.
C.To show how a natural process is interrupted.
D.To explain how humans fight global warming.
3.What does the author want to convey in the last paragraph?
A.We’d better move upstream to live.
B.We should protect plants along rivers.
C.We’d better seek more help from plants.
D.We should be cautious about river management.
4.What is the best title for the text?
A.What Humans Do with Rivers
B.How Rivers’ Transporting Carbon Counts
C.What the Carbon Cycle Means to Us
D.How Living Downstream Affects the Earth
The flu season arrives so predictably, and affects so many of us, that it’s hard to believe that scientists have had very little idea why cold weather helps germs to spread.
Worldwide, up to five million people catch the illness each flu season, and around a quarter of a million die from it. Part of its power comes from the fact that the virus changes so quickly that the body is hardly prepared. “The antibodies we’ve built up no longer recognize the virus – so we lose our immunity,” says Jane Metz at the University of Bristol. It also makes it harder to develop effective vaccines, and even if one comes out, governments often fail to persuade enough people to take it up.
The hope is that by understanding better why flu spreads in winter, but naturally fades in summer, doctors could find simple measures to stop its spread.
Previous theories had centred on our behaviour. We spend more time indoors in the winter, meaning that we’re in closer contact with other people who may be carrying germs.
Another popular idea concerned our physiology(生理机制): the cold weather weakens your body’s defenses against infection. In winter, without much sunlight, we may run low on Vitamin D, which helps power the body’s immune system. Moreover, when we breathe in cold air, the blood vessels in our nose shrink, which affects the normal function of white blood cells, allowing viruses to slip past our defenses unnoticed.
While such factors both play some role, analyses suggested another ignored cause may have been lying invisible in the air that we breathe. Thanks to the laws of thermodynamics(空气热力学), cold air can carry less water vapor before it reaches the “dew point” and falls as rain. So while the weather outside may seem wetter, the air itself is drier as it loses the moisture. And researches in the past few years has shown that these dry conditions seem to offer the perfect environment for the flu virus to flourish.
In wetter air, the epidemic struggles to build strength, while in drier conditions it spreads like wildfire. And comparing 30 years’ climate records with health records, Jeffrey Shaman at Columbia University found that flu epidemics almost always followed a drop in air humidity.
1.What can we infer from the second paragraph ?
A.We lose immunity due to the absence of our antibodies.
B.The antibodies fail to function due to variation of virus.
C.Government should come up with better ways to persuade people.
D.One in four of the infected die from the influenza each flu season.
2.What is the purpose of understanding better why flu spreads in winter?
A.To help develop effective vaccine.
B.To seek ways to treat people infected with flu.
C.To figure out ways to cut off its transmission.
D.To explore how to defend our immune system.
3.In what weather condition a flu epidemic is more likely to occur ?
A.Destroying bodies’ immune system.
B.Powering our bodies’ immune system.
C.Killing numerous viruses that we take in.
D.Stopping us acquiring enough Vitamin D.
4.What is the best title of the passage?
A.Ways to prevent infection of flu B.Flu-A disease not so hard to prevent
C.A predictable flu season D.Why germs spread in winter
Below is a housing guide for students going to London.
University accommodation(住所) offices
Many university accommodation offices have their own list of registered landlords (房东). Others also provide information on accommodation agencies and other housing organizations. The advantage of using your university accommodation office is that you can get some support if you have a problem. The disadvantage is that they are unlikely to have enough registered landlords to house all their students.
Property papers: Loot and Renting
Loot is an important source (来源) of information about private housing for co-renters. The offers are from private landlords, agencies and individuals looking for other co-renters. They also have a website: www. loot. com. The advantage of using Loot is that there are some excellent bargains. The disadvantage is that there is no quality control over the offers.
Renting is another useful paper. The offers in this paper are mainly from accommodation agencies. Their website is at www. Renting.co. uk.
Accommodation agencies
The majority of rented accommodation in London is probably advertised through accommodation agencies. The advantage of using accommodation agencies is that you will have access to a large number of accommodations. A good agent will listen to your requirements and can save you time in looking for the right accommodation. The disadvantage is that they will make a range of charges to potential renters.
Noticeboards
Around the universities you will find a number of noticeboards where offers of accommodation will be posted. These will either be from landlords or from students. Some universities will also have online noticeboards where students can advertise to other students. Advertisements from students can be an excellent way to find accommodation. However, advertisements from landlords can be problematic.
Word of mouth
Some of the best housing in London is never advertised but is passed on from one group of students to another by word of mouth. It might be that you can find out about good offers from final year students. However, don’t suppose that just because you have found out about housing from a friend it is necessarily, going to be better than that found through any other source.
Family
Faced with the very high rents charged in London, some students and their parents will consider buying as an alternative. In some cases this might be a good choice.
1.What is the advantage of using Loot?
A.There are some good bargains.
B.Their website is designed mainly for students.
C.It gives you personal information about other co-renters.
D.It has more offers from accommodation agencies than Renting.
2.A good agent can help you .
A.know more people
B.find cheap accommodation
C.get the right accommodation quickly
D.get free information about most accommodations
3.For students going to London for the first time, which of the following provides the most reliable information?
A.University accommodation offices. B.Loot and Renting.
C.Noticeboards. D.Family.
听下面一段独白，回答以下小题。
1.Why did Fagin come to the speaker?
A.To buy her house. B.To rent her house. C.To decorate her house.
2.Why was the speaker hesitant about Fagin’s offer?
A.She disliked him.
B.The money was not much.
C.They’d damage some of her belongings.
3.How long did it take to prepare the house for the film?
A.Four days. B.A month. C.Two months.
4.What did the speaker do when the crew left?
A.She watched a film.
B.She visited her relatives.
C.She repainted the living room.
听下面一段较长对话，回答以下小题。
1.Which city does the man book a shuttle bus for?
A.London. B.Milton. C.Toronto.
2.What is the woman doing?
A.Conducting an interview.
B.Offering the flight timetable.
C.Taking the man’s information.
3.When will the man probably leave for Milton?
A.At 11:30. B.At 12:00. C.At 12:30.
4.What does the woman advise the man to do?
A.Have some coffee.
B.Collect his luggage first.
C.Book his return ticket in advance.
听下面一段较长对话，回答以下小题。
1.What is the purpose of the call?
A.To accept a position.
B.To advertise a job opening.
C.To check on a job application.
2.For what day is the man’s appointment scheduled?
A.Tuesday. B.Thursday. C.Friday.
3.What does the woman ask the man to do?
A.Call her later.
B.Wait at the front desk.
C.Meet with Victoria Smith.
