来自：查字典高考网 2014-12-25
questions 1l-20
according to some scientists， migratory birds should be able to withstand the winter.
a bird s feathery coat is good insulation against the cold. because a bird is warm- blooded， its body temperature always remains constant， even if the temperature of its surroundings changes.
the factors that trigger migratory behavior in birds are difficult to explain. this behavior seems to be instinctive， not learned. for example， many northern species leave their summer homes while the weather is still warm and the food supply plentiful. young arctic terns born at the arctic breeding grounds will lake off with the flock for distant lands they have never seen.
bird migrations are probably regulated by the glandular system. scientists suspect that the changing length of the day is the factor that triggers migratory behavior. in an experiment， migratory birds were kept in artificially lighted rooms. it was found that if periods of darkness were lengthened proportionately， the glands of the birds became active. these glands secrete hormones， which are chemicals that control numerous body functions. shorter periods of daylight seem to change the hormone balance of birds， so that they retain more fat. this stored fat is the fuel that provides the energy for a long flight. the same experiment revealed that the birds became more excited as the artificial night was lengthened. it is probably no coincidence that most flocks begin their migratory flights during the night.
11. what does the passage mainly discuss？
common migratory paths for birds
why birds migrate
species of birds that do not migrate
migration in cold climates
12. the word withstand in line 1 is closest in meaning to
prefer
tolerate
regulate
understand
13. according to the passage， which of the following protects birds against cold weather？
glands
hormones
feathers
artificial light
14. the word constant in line 3 is closest in meaning to
invariable
persistent
predictable
responsive
15. the word its in line 3 refers to
【托福（TOEFL）考试阅读模拟试题（7）】相关文章：
[标签：海外留学,语言考试,托福,,]
美术联考用纸上海考试模拟试卷纸高考统考纸 4k水粉纸素描纸 速写纸卡纸美术模拟测试试卷纸 美术考试专用纸
探秘历史 第二季 第479集 河南叛逆高考生，写下8000字批判作文，现状如何？
爆笑班主任 第一季 第221集 高考结束学生有多疯狂？山东王老师疯狂吐槽
学渣儿子高考，英语选择题全选B！老师通报成绩的那一刻父亲懵了
NBA流言收割机 第6集 神预测？高考数学试题暗示猛龙勇士4
amc传媒音乐影像 第一季 第600集 高中校长演唱《记忆花园》为高考学子助力打气
衍声高考琴行2019高本硕学生暑假音乐会 张俊瀚《陕北民歌主题变奏曲》《阿根廷舞曲》第三乐章
高中语文知识清单高考语文总複习工具书第5次修订五全綵版五三曲一线科学备考基础知识手册知识大集结资料书参考书导书高一高二高三
