填空题

How Deer Survive Winter Like most of the wild animals, deer survive the cold winter by using energy stored in the summer and fall, usually in the form of (1) ______.They also 1. ______. spend (2) ______ energy in winter than in 2. ______. summer. Deer always give birth to their fawns in May or June. This is good (3)______, because it 3. ______. coincides with the time when plenty of new plants are available. The mother deer must have enough food both to meet the needs of their own bodies and to produce (4) ______ for their fawns. As 4. ______. the fawns grow, they become less and less (5) ______on their mothers. As winter comes, 5. ______. deer’s hair becomes darker and (6)______. 6. ______. Besides, nature provides another (7)______to 7. ______. help them survive the cold weather. They become somewhat slow and drowsy. Their heart rate (8).______.This is an internal physiological 8. ______. response which is to (9) ______their cost of 9. ______. energy. All these practices and responses that increase deer’s chances of survival in winter are the result of thousands of years of (10) ______. 10. ______.

【参考答案】

evolution