1.阅读下列短文，从每题所给的四个选项(A、B、C和D)中，选出最佳选项，并在答题卡上将该项涂黑。

　　NASA's Mars detector—Opportunity，succeeded in finding signs that water once existed on the planet. Opportunity landed on Mars in January. Scientists now believe that the planet could once have supported life.

　　This discovery was chosen by Science，one of the world's leading magazines，as the most important scientific achievement of 2004 last Friday.

　　“This little，wheeled，one­armed box goes around another planet and has done something no human has ever managed，” according to Science. “It has discovered another place in the universe where life could once have existed.”

　　“Although we still can't say that life could have existed in the environment，it is now certain that there was water on Mars，” said Steve Squyres，one of the scientists working on the Mars mission.

　　The evidence comes from pictures and chemical readings taken by Opportunity. It includes marks on rocks like those caused by flowing water on Earth and salty chemicals like those found in dried­out seabed. Scientists said the new evidence proved beyond doubt that water had existed on Mars. But it is still unknown whether the water on Mars was like an ocean or just ice.

　　While Opportunity has not found any signs of life, the presence of water means life is possible. “In everything we know about life on Earth, there is no example without liquid water，” Squyres said. “So water is important for the search for life on Mars.”

　　Researchers agree that a future mission should bring back physical samples. But some scientists worry about the risk that this could introduce dangerous foreign creatures to Earth.

　　“The problem here is how to get the samples back，” Squyres replied. “I think it is our responsibility to limit any risk.”

（1）The best title of the passage should be________．

A．A Finding on Mars              B．Water Means Life

C．Water on Mars               D．The Sign of Water

（2）We can infer from the passage that________．

A．humans will find new creatures on Mars in near future

B．physical samples will surely be brought back to Earth someday in a way

without any risk

C．human beings can fight against the dangerous creatures from the Mars

D．more responsible researchers wanted to carry out the mission

（3）What does the underlined word “detector” mean?

A．An instrument which is used to discover something.

B．An astronaut who has been sent up into space.

C．A scientist who does research on Mars.

D．A spaceship which can land on other planets.