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【单选题】People once widely believed that intelligent life existed on Mars. The 19th-century discovery of what appeared to be geometric designs cut across the surface was taken as evidence. The lines were thou...
A.
The meteorite containing organic compounds is part of Mars.
B.
A Martian rock struck Earth about 11,000 years ago.
C.
The organisms came back to life after the collision with Earth.
D.
The inhabiting organisms appeared more than three billion years ago.
【单选题】People once widely believed that intelligent life existed on Mars. The 19th-century discovery of what appeared to be geometric designs cut across the surface was taken as evidence. The lines were thou...
A.
the minor geologic characteristics of Mars
B.
natural valleys on the surface of Mars
C.
rivers that have kept flowing since ancient times
D.
a system that irrigates the whole surface
【单选题】People once widely believed that intelligent life existed on Mars．The 19th-century discovery of what appeared to be geometric designs cut across the surface was taken as evidence．The lines were though...
A.
Because the surface of Mars seemed to be geometric.
B.
Because the lines were drawn across the surface of the planet.
C.
Because a system of canals was thought to be there.
D.
Because it was the Martians that built the canals.
【单选题】For centuries, explorers have risked their lives venturing into the unknown for reasons that were to varying degrees economic and nationalistic. Columbus went west to look for better trade routes to t...
A.
To find out if life ever existed there.
B.
To see if humans could survive there.
C.
To prove the feasibility of large-scale space ventures.
D.
To show the leading role of science in space exploration.
【单选题】For centuries, explorers have risked their lives venturing into the unknown for reasons that were to varying degrees economic and nationalistic. Columbus went west to look for better trade routes to t...
A.
to display their country"s military might
B.
to accomplish some significant science
C.
to find new areas for colonization
D.
to pursue commercial and state interests