sentences: if a living thing becomes too cold then that living thing will die & an animal is a kind of living thing ->  if an animal becomes too cold then that animal will die  if an animal becomes too cold then that animal will die & keeping warm is the opposite of becoming cold ->  an animal requires warmth for survival  an animal requires warmth for survival & if the environmental temperature / air temperature is too cold then an animal / a living thing in that environment may become cold ->  an animal requires warmth for survival in cold environments  cold environments have cold temperatures / weather & climate is the average weather / temperature in an area ->  a cold environment means a cold climate  an animal requires warmth for survival in cold environments & layers of fat are used to keep animals warm ->  layers of fat are used by animals to survive in cold environments by keeping warm  layers of fat are used by animals to survive in cold environments by keeping warm & traits that help animals survive in a certain kind of environment are often found in animals in that environment ->  layers of fat are often a part of animals that live in cold climates  layers of fat are often a part of animals that live in cold climates & blubber is a kind of fat -> blubber is often a part of animals that live in cold climates