217 -According to the passage, so far, ---- .
A) the Apollo spacecraft has brought back several pieces of comets
B) NASA has regularly sent missions to bring back material from outer space
C) the "Stardust" spacecraft has completed some other major missions
D) pieces of a comet haven't been brought back from space by NASA
E) the comet Wild -2 has never come close to the Sun
218 -The passage suggests that the Wild -2 comet --- .
A) came close to the Sun for the first time in 1970
B) travels about 5.1 billion kilometres every seven years
C) was discovered In the 1970s
D) probably consists partly of frozen material
E) is the first comet to come dangerously close to the Earth
Do'stlaringiz bilan baham: |