单选题Sharing accommodation may be ______.A approximately A$10, 000 per year cheaper than living alone.B more expensive than living alone.C not suitable for some students.D suitable for most students.

At the first sight the planet Mars does not appear very welcome to any kind of life．It has very little oxygen and water,the temperature at night is below-50~Cand winds of 100 miles per hour cause severe dust storms．However,the surface of the planet seems to show that water flowed across it some time in the past,and it is believed that there is enough ice at the poles to cover the planet with water if it melts．Although there is no life on the Mars now,some scientists think that there may have been some form of life long time ago．At that time,the planet had active volcanoes;the atmosphere was thicker and warmer;and there was water．In fact,in some ways the Mars may have been similar to the Earth,where life exists.
Some people believe that the Mars could support life in the future if the right conditions were produced．The first step would be to warm the planet using certain gases which trap the Sun's heat in the planet's atmosphere．With warmth,water and carbon dioxide(二氧化碳),simple plants could begin to grow．These plants could slowly make the Mars more suitable for living．It is estimated that the whole process might take between 100,000 and 200,000 years．In the meantime,people could begin to live on the planet in special closed environments．They would provide a lot of useful information about conditions on the Mars and the problems connected with living there.

Some scientists think there may have been life on the Mars in the past because__.

A.there is no life there now
B.there is a large amount of water at the poles
C.the Mars may be able to support life in the future
D.conditions may have been similar to those on the Earth

Rainfall in most of the Sahara is________.

A) less than five inches per year
B) less than ten inches per year
C) less than twenty inches per year
D) zero

At the first sight the planet Mars does not appear very welcome to any kind of life．It has very little oxygen and water,the temperature at night is below-50~Cand winds of 100 miles per hour cause severe dust storms．However,the surface of the planet seems to show that water flowed across it some time in the past,and it is believed that there is enough ice at the poles to cover the planet with water if it melts．Although there is no life on the Mars now,some scientists think that there may have been some form of life long time ago．At that time,the planet had active volcanoes;the atmosphere was thicker and warmer;and there was water．In fact,in some ways the Mars may have been similar to the Earth,where life exists.
Some people believe that the Mars could support life in the future if the right conditions were produced．The first step would be to warm the planet using certain gases which trap the Sun's heat in the planet's atmosphere．With warmth,water and carbon dioxide(二氧化碳),simple plants could begin to grow．These plants could slowly make the Mars more suitable for living．It is estimated that the whole process might take between 100,000 and 200,000 years．In the meantime,people could begin to live on the planet in special closed environments．They would provide a lot of useful information about conditions on the Mars and the problems connected with living there.

The author's attitude towards the possibility of life on the Mars in the future is__.

A.doubtful
B.positive
C.negative
D.uninterested

资料：Up to 80 per cent of the world’s middle classes will live in developing countries by 2030 thanks to surprising recent gains in poverty reduction, according to a United Nations report published on Thursday.
“Never in history have the living conditions and prospects of so many people changed so dramatically and so fast.” concludes the UN’s latest Development Report. “The world is witnessing an epochal ‘global rebalancing’.”
Underpinning the improvements in the human development index（HDI） was rapid growth in countries such as China, India and Brazil, with China and India having doubled per capita economic output in less than 20 years. But the study stressed that growth and improvements in HDI spread far beyond the four Bric countries of Brazil, Russia, India and China, and included at least 40 countries that had accompanied greater economic dynamism with effective poverty-reduction policies.
Afghanistan, Sierra Leone, Ethiopia, Rwanda and Angola were among 14 countries that have recorded gains in HDI of more than 2 per cent a year since 2000. Partly as a result, the report found that worldwide extreme income poverty has plunged from 43 per cent in 1990 to just 22 per cent in 2008, including more than 500m being lifted out of poverty in China alone. The report stated that such gains had already helped the world achieve the main poverty eradication goal of the so-called Millennium Development Goals, which called for the share of people living on less than $1.25 a day to be cut by half from 1990 to 2015.
Underpinning this poverty reduction was developing countries’ increasing share of global trade, which grew from 25 per cent to 47 per cent between 1980 and 2010. “The south as a whole is driving global economic growth and societal change for the first time in centuries,” says the report.
The report found that trade among developing countries was the biggest factor in that expansion, increasing from less than 10 per cent of total global trade to more than 30 per cent. “Trade between countries in the south will overtake that between developed nations,” the report said.

“More than 500m being lifted out of poverty in China alone” illustrates ______.

A.the economic development of China is important
B.the role of some developing countries is significant for poverty reduction
C.14 countries are developing faster than China
D.it is crucial to make a clear goal first