时间:2018-12-27 作者:英语课 分类:英语时差8,16


英语课

 Last time we were thinking about why some birds hop 1 and other birds walk. We decided 2 that you can't make any blanket statements about this, because there will always be exceptions. But in general it's true that larger birds are more likely to walk and smaller birds to hop, just because of the amount of energy it takes. But there's more to it than that. Ornithologists are actually very interested in bird legs and feet. The differences between different kind of legs are used in bird classification. For example, what we commonly call "songbirds"--cardinals, wrens 3, mockingbirds, warblers--are also called "perching birds." They have specialized 5 structures in their feet that include three toes pointing forward and one more called the "hallux" that points back. That three-and-one design is excellent for holding on to branches, which is an important skill to possess if you are a bird. Okay, so far so good. But now, what does that kind of foot make more difficult? You got it--a foot with a conspicuous 6 hallux toe won't be very good at walking. Some birds manage it, and there are different kinds of hallux toes that make it easier or harder. But to move around with feet like that, sometimes you just might be better off hopping 7. So, evolution has to make a choice. Is it better to perch 4 safely on branches or walk comfortably on the ground? Do I catch food with my feet or my beak 8? And so on. The end result can be birds with different kinds of feet, and different kinds of walks.



1 hop
n.单脚跳,跳跃;vi.单脚跳,跳跃;着手做某事;vt.跳跃,跃过
  • The children had a competition to see who could hop the fastest.孩子们举行比赛,看谁单足跳跃最快。
  • How long can you hop on your right foot?你用右脚能跳多远?
2 decided
adj.决定了的,坚决的;明显的,明确的
  • This gave them a decided advantage over their opponents.这使他们比对手具有明显的优势。
  • There is a decided difference between British and Chinese way of greeting.英国人和中国人打招呼的方式有很明显的区别。
3 wrens
n.鹪鹩( wren的名词复数 )
  • Other songbirds, such as wrens, have hundreds of songs. 有的鸣鸟,例如鹪鹩,会唱几百只歌。 来自辞典例句
4 perch
n.栖木,高位,杆;v.栖息,就位,位于
  • The bird took its perch.鸟停歇在栖木上。
  • Little birds perch themselves on the branches.小鸟儿栖歇在树枝上。
5 specialized
adj.专门的,专业化的
  • There are many specialized agencies in the United Nations.联合国有许多专门机构。
  • These tools are very specialized.这些是专用工具。
6 conspicuous
adj.明眼的,惹人注目的;炫耀的,摆阔气的
  • It is conspicuous that smoking is harmful to health.很明显,抽烟对健康有害。
  • Its colouring makes it highly conspicuous.它的色彩使它非常惹人注目。
7 hopping
n.鸟嘴,茶壶嘴,钩形鼻
  • The bird had a worm in its beak.鸟儿嘴里叼着一条虫。
  • This bird employs its beak as a weapon.这种鸟用嘴作武器。
学英语单词
acclivi-tous
Acer platanoides
additional paragraph in auditor's report
air-brake dynamometer
Ammate
anchorable
Andreyevskiy
apertura
ashtanga
astatic
auriculo-ventricular
bequeathest
bicornuta
biotransfer
Blenheim Orange
calculus of lower urinary tract
callionymus variegatus
charge-sheet
chernyy otrog
collcynth
comma movable
community-gardening
contagious polyarthritis
corocalene
counter clockwise (ccw)
counterefforts
crowflower
de-esterification
deficit covering bonds
desalin(iz)ation
dichlorbenil
ecureuils
entero-chromaffin cell
explosive pressure
financial environment
fluxgate magnetometer
Fogg Art Museum
fulguration current
Gastrocybe lateritia
generator field control
get the memo
gibelike
graphics adapter
grating of gears
gunnery practice
hematopoietic system
high-voltage switch
hylozoism
hypersonic glider
ideal imperfect-crystal
ill-natured
illegal condemnation
intergroup behavior
klier
koe-san (goesan)
komun-som (huk-to )
lathe tool bit
lending agreement
like kings
lindahl taxes
main longitudinal frame
microflake tobacco sbeet
micropegmatitic structure
ministry for industry and trade
minor orders
momchaunce
National city Bank of New York
neutron activity
normalization routine
oceanic affinity
oxyphosphate of copper cement
palm-presser
parameter plane method
pasteurized lactic beverage
peneite
phase diagram of reservoir hydrocarbon
photoactivity detector
playdoh
plug for seal
printergram
refuse incinerator
repairable material
rhizocephalous
rusticalness
science teachers
seeabler
seeing about
ship technology
siccitate
Sisymbrium officinale
snakeskin glaze
spreader-ditcher
stand point
standing-wave method
stroke ... down
stuffing gland
truncheoning
trustor
ursaenate
VREPAIR
wanderstars