题目

NASA’s Mars detector (探测器), 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, one-armed box went 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.” 7千米=70007000米 90毫米=99厘米 70厘米=77分米 5吨=50005000千克 1吨-700千克=300300千克 3千米+1000米=40004000米．