Many kinds of animals are believed to have _________from the earth
B
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Theengineersinthislabspentseveralweeks_______theirplansforthenewbicycle.
Weare_______attherapidprogressMarkhasmadeinthissemester.
Whenaspacecrafttravels,oneofthemajorproblemsisreentryintotheEarth’s_______.
Itisnot---_______formetoreturnallthebookstothelibrarynowbecauseIstillneedsomeofthemformyresearch.