首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
How does a whale keep itself warm?
How does a whale keep itself warm?
admin
2018-04-19
33
问题
How does a whale keep itself warm?
Millions of years ago, whales lived on land and walked on four legs. Today, whales still have small bones that are the remains of their hind legs, but these bones can only be seen on the inside of the whale. No one knows why whales left the land to live in the water.
However, scientists can imagine that when the whales changed their environment, their bodies underwent a change—taking on a more fish-like appearance. This new form offered less resistance to the water, enabling the whales to swim faster.
Despite their fish like form, whales are not fish. A whale will drown, just as a man will, if it stays under water too long. When a whale is under water, it closes its nostrils tightly and holds its breath. The air in its lungs becomes very hot and full of water vapor. When the whale rises to the surface and exhales, its hot breath produces a column of water vapor that rises high in the air. A man produces the same effect when he exhales warm air on a cold morning.
Whales are classified as mammals because they bear their young, rather than laying eggs, and because the mother whales give the babies milk. Like other mammals, whales have warm blood. Their blood stays at the same temperature, even when they move from hot to cold water. They keep warm in cold water because they have a thick layer of fat just under their skins. This fat is called blubber, and it is thicker on whales that spend their lives in cold water. Almost all land mammals, except man, have hair on their bodies to keep them warm, but whales, which have very few hairs, are kept warm by their fat.
选项
A、They have very few hairs on their bodies.
B、They bear their young rather than laying eggs.
C、Their lungs are full of hot air and water.
D、They can walk on their hind legs on land.
答案
A
解析
转载请注明原文地址:https://kaotiyun.com/show/arRd777K
本试题收录于:
公共英语四级笔试题库公共英语(PETS)分类
0
公共英语四级笔试
公共英语(PETS)
相关试题推荐
Orchidsareuniqueinhavingthemosthighlydevelopedofallblossoms,inwhichtheusualmaleandfemalereproductiveorgansa
Moviegoersmaythinkhistoryisrepeatingitselfthisweekend.Thesummer’smostanticipatedfilm,PearlHarbor,whichhasopene
Moviegoersmaythinkhistoryisrepeatingitselfthisweekend.Thesummer’smostanticipatedfilm,PearlHarbor,whichhasopene
Whatdowelearnaboutthespeaker?
Thehorseandcarriageisathingofthepast,butloveandmarriagearestillwithusandstillcloselyinterrelated.MostAmer
MostworthwhilecareersrequiresomekindofspecializedtrainingIdeally,therefore,thechoiceofan【21】______shouldbe
Whatisthespeakertalkingabout?
1,050pounds
InNewZealandChristmasDayitselfisobservedmuchthesamewayasitisintheUnitedStatesandEurope.(61)Therearesome
Irememberthewaythelighttouchedherhair.Sheturnedherhead,andoureyesmet,amomentaryawarenessinthatraucousfift
随机试题
腹部九分法,下水平线为
木门窗五金配件的安装,下列哪项是错误的?[2006-115]
在建设项目财务评价中,当财务净现值为( )时,项目方案可行。
下列关于收益计量的说法,正确的是()。
阅读下面材料,回答问题。李华是一个十分聪明的学生,他的最大特点就是贪玩,学习不用功。每次考试他都有侥幸心理,希望能够靠运气过关。这次期末考试他考得不理想,他认为这次是自己的运气太差了。请运用维纳的归因理论来分析:如不正确,正确的归因应是怎样
标志着十年内战的局面由此结束,国内和平基本实现,成为时局转换的枢纽的是()
有如下定义:classInner{public:voidf1(){cout
对要求输入相对固定格式的数据,例如电话号码010-83950001,应定义字段的( )。
Terrywasimpressedwith______.
A、Hemovedthethreadawayfromtheneedle.B、Heusedspearsinsteadofneedle.C、Hetriedtogetthethreadtorunaroundthen
最新回复
(
0
)