Final answer:
The sentences are completed using comparative adjectives to describe various subjects.
Step-by-step explanation:
1. The Cheetah is faster than any other animal in the world.
2. The Nile River is longer than any other river in the world.
3. The Atlantic Ocean is the widest ocean on Earth.
4. Australia is the smallest continent.
5. The Blue whale is the largest animal on Earth.
6. Antarctica is the coldest place on Earth.
7. Mars is the closest planet to the sun.
8. Mount Everest is the highest mountain on Earth.
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