时间:2018-12-30 作者:英语课 分类:托福听力短文


英语课
(woman) To us, the environment in which fish dwell often seems cold, dark, and mysterious. But there are advantages to living in water, and they have played an important role in making fish what they are. One is that water isn't subject to sudden temperature changes. Therefore it makes an excellent habitat for a cold-blooded animal. Another advantage is the water's ability to easily support body weight. Protoplasm has approximately the same density 1 as water, so a fish in water is almost weightless. This "weightlessness" in turn means two things: One, a fish can get along with a light weight and simple bone structure, and two, limitations to a fish's size are practically removed.

Yet there is one basic difficulty to living in water --- the fact that it's incompressible. For a fish to move through water, it must actually shove it aside. Most can do this by wiggling back and forth 2 in snakelike motion. The fish pushes water aside by the forward motion of its head, and with the curve of its body and its flexible tail. Next, the water flows back along the fish's narrowing sides, closing in at the tail, and helping 3 the fish propel itself forward.

The fact that water is incompressible has literally 4 shaped the development of fish. A flat and angular shape can be moved through water only with difficulty. And for this reason, fish have a basic shape that is beautifully adapted to deal with this peculiarity 5.


n.密集,密度,浓度
  • The population density of that country is 685 per square mile.那个国家的人口密度为每平方英里685人。
  • The region has a very high population density.该地区的人口密度很高。
adv.向前;向外,往外
  • The wind moved the trees gently back and forth.风吹得树轻轻地来回摇晃。
  • He gave forth a series of works in rapid succession.他很快连续发表了一系列的作品。
n.食物的一份&adj.帮助人的,辅助的
  • The poor children regularly pony up for a second helping of my hamburger. 那些可怜的孩子们总是要求我把我的汉堡包再给他们一份。
  • By doing this, they may at times be helping to restore competition. 这样一来, 他在某些时候,有助于竞争的加强。
adv.照字面意义,逐字地;确实
  • He translated the passage literally.他逐字逐句地翻译这段文字。
  • Sometimes she would not sit down till she was literally faint.有时候,她不走到真正要昏厥了,决不肯坐下来。
n.独特性,特色;特殊的东西;怪癖
  • Each country has its own peculiarity.每个国家都有自己的独特之处。
  • The peculiarity of this shop is its day and nigth service.这家商店的特点是昼夜服务。
学英语单词
about one's ears
abstention line
adjustable rod
alkalophilic bacterium
alkylatings
andrea guarneris
auxiliary field fuse
Beaufortin
beday
Beko
bend cutting tool
biofabric
Bonnet,Charles
boring-tool
calliopiids
car medium repair
carbonyls
co-resident
compound die
coordination in system
creeping therophytes
dead wegith cargo capacity
development expenditure
dhuodas
differential draught gauge
direct repatriation
drag acceleration
duplex lock
Eastgate
effluent weir
eikmeyer
Einstein equation of the field of gravity
flowstones
frost-making
fuccboi
gamaleia's spirillum
gardenage
gaze round
get fame
goose-dung ore
heterochronic rhythm
iiic
Ilex micropyrena
IMIA
influence mine sweeping
ingly
interactive general accounting system
interferonopathy
ion exchange analysis
keep a House
Kismaayo
knob-head
lecanuets
length of tube
Lincoln's Birthday
long routing
magneto machine
mesoblastic band
methyl toluate
minimum en-route altitude
moufflons
mousie
multidimensional Turing machine
n.d.a.
neo-volcanic rock
newton cooling law
omitters
on-line digital analog simulator
orthogeriatric
oxygen-deficient combustion
papalist
paries superior orbitae
percent reduction
peroxy-
pi section filter
pituophiss
plane membrane
policy advocacy coalition
pulao
Radovici's sign
Rhododendron ellipticum
Rhododendron liliiflorum
rosid
sample room
servant-girl
shipborne magnetic survey
solid head
starch crescent
stencilplate
subroutine libraries
synchro pickoff
tank locomotive
teach-in
thaumatins
timer timing pulse
tinpots
travelling bed
Trojan planet
twisk
Vic-en-Bigorre
Yefrem