Koalas sleep for about 16 to 18 ..... per day.

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Koalas sleep for about 16 to 18 ..... per day. (*) lifetimes (*) years (*) hours (*) weeks

This is a companion discussion topic for the original entry at https://english.best/questions/19000,koalas-sleep-for-about-16-to-18-___-per-day/