551.Once positioned in space, the Hubble Space Telescope will capture light from sources twenty times fainter compared to those that can be detected by ground-based instruments.
　　(A) compared to those that can be detected
　　(B) compared to those they can detect
　　(C) than that can be detected
　　(D) than those that can be detected
　　(E) than those detecting
　　the key:D
　　比较考点：比较对象。sources——those that can be detected
　　562.One reason why more young people lose their virginity during the summer than at other times of the year undoubtedly is because school vacations give adolescents more free time.
　　(A) One reason why more young people lose their virginity during the summer than at other times of the year undoubtedly is because
　　(B) If young people lose their virginity more during the summer than other seasons, it is undoubtedly because
　　(C) One undoubtable reason that young people lose their virginity more during the summer than other times is
　　(D) One reason more young people lose their virginity during the summer than at other times of the year is undoubtedly that
　　(E) Young people lose their virginity more often during the summer undoubtedly because, for one reason,
　　the key：D
　　比较考点：比较对象。during the summer——at other times of the year