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
temperature
cold
coat
bird
16. in lines 7-9， the author mentions young arctic terns as an example of birds that
do not migrate
breed during migration
migrate instinctively
adapt to the cold
l7. the word they in line 16 refers to
glands
birds
body functions
hormones
18. according to the passage， birds exposed to longer periods of darkness experience all of the following changes except
activated glands
excited behavior
retention of more fat
increased appetite
19. in the experiment mentioned in the passage， the scientists adjusted the birds
food supply
body temperatures
exposure to light
brain chemistry
【托福（TOEFL）考试阅读模拟试题（7）】相关文章：
[标签：海外留学,考试,托福,,]
他高考作文仅得6分，总分428分，被985高校录取，却被导师拒绝！
张雪峰高考志愿填报指南 第28集 高考志愿分析，材料科学与工程专业，就业很一般，建议慎重选择
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
一边扔试卷一边玩摇滚？这个学校的高考减压方式，真是帅到没朋友
沈阳音乐学院郎亦农教授的女高音高考曲目解析课程 第1集 沈阳音乐学院郎亦农为你讲解女高音高考曲目
高考阅卷名师给考生的高考作文密训课 第5集 高考作文审题实操方法精讲（三）
优秀！英语数学双满分，广西“最牛”高考状元730分刷新最高纪录
