1 . Mars is no stranger to life. Seven U. S. spacecraft have successfully landed there, and all of them took microbes to the planet’s surface(though the bugs probably did not survive for long). Yet the world’s space agencies continue to maintain strict spacecraft sterilization (消毒) procedures in the hope of minimizing the spread of Earth life beyond our planet. For decades this idea — known as planetary protection—is widespread. Now, some scientists say, these procedures are preventing the search for life beyond Earth by raising costs and preventing innovative missions-without meaningful benefits.

Of all missions to Mars to date, only the Vikings, the first trip to the Red Planet, were intended to test for life. Spacecraft that went later did not have that ability. But a future mission will, and the protectionist thinking goes, a spacecraft might not be able to distinguish between a life form native to Mars and one with origins on Earth. In July 2013 astrobiologists Dirk Schulze-Makuch and Alberto Fairen argued against this in Nature Geoscience.

“If Earth life can thrive on Mars, they almost certainly already do,” the authors write. “If they cannot, the transfer of Earth life to Mars should be of no concern, as it would simply not survive.”

With clear evidence of a water y history and some signs of water present, Mars could be where we find life in our solar system. And with the development of Curiosity’s precise landing system, we can finally reach the mysterious parts of the planet. But it’s these areas that require a craft sterilization process.

In the 1970s Vikings 1 and 2 revealed what seemed like a dead planet, so planetary-protection requirements were relaxed. Now, with more knowledge of Mars’ environment, missions set to visit areas with evidence of flowing water below the surface have to meet the strict-and more costly- Vikings standards.

Finally, there’s the philosophical problem of what responsibility, if any, we have to other planets and any life we leave there. The truth is we’re never going to be able to fully protect Mars if we intend to explore it. And spreading is simply what life does.

“If we want to survive for a long time, we have to expand beyond Earth,” Schulze-Makuch says. “There’s no other way.”

1. Strict spacecraft sterilization procedures are meant to ______.

A．decrease the costs of space exploration

B．help the search for life forms beyond Earth

C．contribute to innovative missions in the universe

D．prevent Earth life being transferred to other planets

2. Planetary-protection requirements were relaxed in the 1970s because ______.

A．there was no preclse landing system

B．Mars was considered to be a lifeless planet

C．the mysterious parts of Mars remained unknown

D．flowing water was found below the surface of Mars

3. Dirk Schulze-Makuch and Alberto Fairen are most likely to agree that ______

A．Mars is now on the edge of being destroyed

B．human beings are too ambitious to expand beyond Earth

C．there is no need to worry about bringing Earth life to Mars

D．we need to be responsible for keeping Mars what it is like now

4. Schulze-Makuch takes a(n)______attitude towards planetary protection.

A．optimistic

B．relaxed

C．debatable

D．negative

2 . Directions: Complete the following passage by using the words in the box. Each word can only be used once. Note that there is one word more than you need.

A. authorities   B. conflicts   C. increasingly   D. infected E. invisibly F. oddly G. outbreaks   H. present   I. subjected   J. suspected   K. unexpected

Deadly virus approaches tigers

India’s most important tiger conservation body is to investigate growing concern that Asia’s wild tigers are     1     to a deadly new disease.

The National Tiger Conservation Authority is to fun d a study of Canine Distemper Virus(CDV) in six of the most important areas for the species, which could confirm a problem that a few experts have     2    for a number of years.

There have been     3    of CDV in wild tigers in other areas. According to Dr Dale Miquelle of the Wildlife Conservation Society, quite a few tigers were either killed or seriously affected by a disease that was probably CDV in 2010. And the Sikhote-Alin Biosphere Reserve has also reported a(n)     4     decline in tiger numbers.

CDV may also exist in the tiger population in Sumatra, where animals have been reported to be behaving     5    and losing their fear of humans.

Dr John Lewis of the British charity Wildlife Vets International is helping the Sumatran    6    to fight the risk by training local vets in what he calls “the world’s first tiger- disease monitoring program”.

Lewis also believes that the way CDV changes tigers’ behavior could be a factor where tiger- human     7    are an issue. This could be true of the Sundarbans, a large area shared by India and Bangladesh where man-eating is spreading.

Perhaps we should not be surprised that tigers are     8    with CDV. In 2004, it killed 1,000 lions in the Serengeti in Tanzania, and as wildlife reserves are    9    surrounded by people with dogs, the problem is only likely to get worse.

But as Miquelle told BBC Wildlife, “Very few people were aware of the potential threat, let alone looking for it, even if it is     10    in the system. But at least now they are.”

3 . A weather map is an important tool for geographers. A succession of three or four maps presents continuous picture of weather changes. Weather forecasters are able to determine the speed of air masses and fronts (冷暖空气团接触的锋) to determine whether an individual pressure area is deepening or becoming shallow and whether a front is increasing or decreasing in intensity. They are also able to determine whether an air mass is retaining its original characteristics or taking on those of the surface over which it is moving. Thus, a most significant function of the map is to reveal a summary picture of conditions in the atmosphere at a given time.

All students of geography should be able to interpret a weather map accurately. Weather maps contain an enormous amount of information about weather conditions existing at the time of observation over a large geographical area. They reveal in a few minutes what otherwise would take hours to describe. The United States Weather Bureau issues information about approaching storms, floods, frosts and all climatic conditions in general. Twice a month it issues a 30-day “outlook” which is a rough guide to weather conditions likely to occur over broad areas of the United States. These 30-day outlooks are based upon an analysis of the upper air levels which often set the stage for development of air masses, fronts and storms.

Considerable effort is being exerted today to achieve more accurate weather predictions. With the use of electronic instruments and satellites, enormous gains have taken place recently in identifying and tracking storms over regions which have but few meteorological stations (气象站). Experiments are also in progress for weather modification (改变) studies. But the limitations of weather modification have prevented meteorological results except in the seeding of super-cooled, upslope mountainous winds which have produced additional orographic (山岳形态) precipitation on the windward side of mountain ranges. Nevertheless, they have provided a clearer understanding of the fundamentals of weather elements.

1. By reading weather maps, students majoring in geography can .

A．design a project of weather modification

B．interpret the weather condition before the time of observation

C．obtain data on atmospheric conditions over a wide area

D．survey ever-changing fronts in local meteorological stations

2. A thirty-day forecast is determined by examining________.

A．daily weather maps	B．upper air levels
C．satellite reports	D．changing fronts

3. The observation of weather conditions by satellites is helpful because ________.

A．electronic instruments are used

B．it enables man to alert the weather

C．it makes weather more time-consuming

D．information not be obtained readily otherwise can be gained

4. At the present time, experiments are being conducted in________.

A．controlling and influencing weather

B．determining density of pressure groups

C．30-day “outlooks”

D．predicting storms