阅读策略：梳理说明文结构 — 英语词汇题
题目
阅读短文，选择恰当的词填空：introduction（引入）、details（说明细节）、conclusion（总结）。① Polar bears live in the Arctic. ② Their thick fur helps them stay warm, and their wide paws help them walk on snow. ③ These features help polar bears survive in a cold environment. 结构顺序：①____ ②____ ③____。