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habitable – adj. able to be lived in
light-year –n. (unit of measure) the distance light travels in one year
determine – v. discover the facts or truth about something
harbor – v. to be the home or habitat of
maintain – v. make a situation or activity continue
composition – n. the parts that something consists of
possess – v. to have or own something
motivate – v. to cause someone to behave a particular way
detect – v. to discover or notice something
