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
2019-01-11
84
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、Grows colder as the blubber accumulates.
B、Remains the same.
C、Varies according to the water temperature.
D、Grows warmer as the whale grows older.
答案
B
解析
转载请注明原文地址:https://kaotiyun.com/show/SORd777K
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
Thepatient,accordingtotheanalyst’sreport,is
(61)Beautyhasalwaysbeenregardedassomethingpraiseworthy.Almosteveryonethinksattractivepeoplearehappierandhealthi
somepeopleprefertoplanactivitiesfortheirfreetimeverycarefully.Otherschoosenottomakeanyplanatallfortheirfr
Theprobablerelationshipbetweenthetwospeakersisdoctorand______.
InNewZealandChristmasDayitselfisobservedmuchthesamewayasitisintheUnitedStatesandEurope.(61)Therearesome
toovercome
showofself-confidence
Itisexcitingtoapplyforajobthatreallyappealstoyou.Inmakingyourapplication,thereareanumberofpointsforyout
Itisexcitingtoapplyforajobthatreallyappealstoyou.Inmakingyourapplication,thereareanumberofpointsforyout
随机试题
体内铁缺乏可分为哪几个阶段,各阶段的特点是什么?
设参加某次考试人数为10657人,其中有6995人的成绩低于90分,试确定卷面90分这个成绩的百分等级PR。(保留2位小数)
若Z作为X和Y的函数,下列回归方程属于线性方程的是()。
金沙遗址出土的()被作为中国文化遗产的标志。
PCM方式的模拟信号数字化要经过()过程。
很少有人具有成为成功的商品贸易商的能力。因此,贸易公司宁愿雇用所有能够成为成功的商品贸易商的申请者而拒绝其余部分,也不愿限定他们雇用的人数。通过这个标准,Qeuinsey—leerheim的记录非常好。在过去的几十年中,该公司所有达到入门水平的雇员都成为了
以下各项中,不属于太阳能利用的主要形式的是()。
下列关于矿产资源的说法中,正确的一项是:
字长是CPU的主要技术性能指标之一,它表示的是()。
•Readthearticlebelowabouttherelationshipbetweentradeanddevelopment•ChoosethebestwordtofilleachgapfromA,B,C
最新回复
(
0
)