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
96
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
WhatisEinstein’sgreatestcontributiontohumanbeings?
HowmanychildrendidSusanandMichaelinterview?
Thespeakermakesanannouncementabouttheafternoon______.
Thespeakermakesanannouncementabouttheafternoon______.
somepeopleprefertoplanactivitiesfortheirfreetimeverycarefully.Otherschoosenottomakeanyplanatallfortheirfr
Inoneverylongsentence,theintroductiontotheU.N.Charterexpressestheidealsandthecommonaimsofallthepeoplewhose
MarianneMoore(1887—1972)oncesaidthatherwritingcouldbecalledpoetryonlybecausetherewasnoothernameforit.Indeed
Standardusageincludesthosewordsandexpressionsunderstood,used,andacceptedbyamajorityofthespeakersofalanguagei
excitingandfulfilling.
Itisexcitingtoapplyforajobthatreallyappealstoyou.Inmakingyourapplication,thereareanumberofpointsforyout
随机试题
TheearliestimmigrantstoNorthAmericafoundIndiansalreadylivingthere.TheIndiansnumberedabout500,000atthattime.Th
氯丙嗪降温作用的特点不正确的是
注射用脂肪乳剂常用的乳化剂有()
女婴,10个月。腹泻3天,加重2天。暗红色水样便每日10余次,量多,腥臭,伴高热、呕吐、少尿。查体:精神萎靡,呈嗜睡状,前囟眼窝凹陷,皮肤弹性差,心音较低钝,腹胀,肝脾不大。实验室检查:粪镜检有大量脓血细胞,血钠135mmol/L,血钾3.5mmol/L。
用承载板测试土基回弹模量,在逐级加载卸载过程中应()。
下列关于刑事诉讼案件的上诉与抗诉说法正确的是()。
香港甲公司收购境内乙公司部分资产,并以该部分资产作为出资与境内丙公司于1998年3月1日成立了一家中外合资经营企业。甲公司收购乙公司部分资产的价款为120万美元。下列选项中,不符合外商投资企业法律制度规定的价款支付方式有()。(1999年)
调控社会总需求的两大支柱政策是()。
“人只有受过一种合适的教育之后,人才能成为一个人。”这说明教育是()。
某汉字的国际码是1112H,它的机内码是
最新回复
(
0
)