In Nelis Nature Reserve, Alaska, there was a story that attracted wolves to compete for deer. It turns out that people kill local wolves to protect deer, so deer have no natural enemies and eat happily in the forest all day. Ten years later, the number of deer increased from 400 to 40 thousand. However, the deer's posture is stupid and has lost its former beauty. Due to the rapid reproduction and trampling of deer, plants also withered. Deer died in large numbers because of lack of enough food and physical weakness caused by ease and inactivity. So people invited the wolf in again, and the deer ran desperately, and the reserve recovered its old vitality.

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Material to write an argumentative essay, the topic was born in worry and died in happiness.