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题库 / OG13-SC-45
Quasars, at billions of light-years from Earth the most distant observable objects in the universe, believed to be the cores of galaxies in an early stage of development.
believed to be
are believed to be
some believe them to be
some believe they are
it is believed that they are
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the most distant observable objects in the universe这个跟在at billions of light-years from Earth后面是什么意思
the most distant observable objects in the universe这个跟在at billions of light-years from Earth后面是什么意思
CDE没有谓语，A中Quasars应该是被相信