单项选择题
| Mars is not, it seems, the dry old
planet we once believed it to be. Astronauts who are (1) to
go there in the next decade may find plenty (2) water to
slake(消除) their thirst. And with water present the (3) of finding some sort of life on Mars are (4) brighter. This is the view of 40 (5) all over the world who have been analyzing (6) of pictures and other scientific (7) obtained by robot explorers in the sixties and seventies. To begin with, scientists thought the Red Planet was as (8) as the Moon with dust storms swirling over vast sandy (9) . But now the picture is very different with mountains and valleys carved by (10) glaciers and torrential rivers rushing and rumbling deep underground. In a report on the (11) of the Martian pictures Dr. Michael Car of the U.S. Geological Survey comments, "I am (12) there’s lots of water on Mars." Any surface water will be in the (13) of ice. But it could (14) explorers having to take so much fresh (15) with them. The report says (16) Mars probably had a warmer climate in ages (17) due to its axis having been more steeply tilted towards the Sun. (18) convincing signs of plant or animal life have been (19) by instruments soft. landed on Mars, (20) only the immediate vicinity of landing vehicles could be examined. |