23 Bird Flight

名称：23 Bird Flight
内容简介：
新概念英语第四册（英音）
[al:新概念英语（四）]
[ar:MP3 同步字幕版（英音）]
[ti:Bird Flight]

[00:01.53]Lesson 23
[00:03.66]Bird flight
[00:11.29]What are the two main types of bird flight described by the author?
[00:17.83]No two sorts of birds practise quite the same sort of flight;
[00:22.47]the varieties are infinite; but two classes may be roughly seen.
[00:28.50]Any ship that crosses the Pacific
[00:30.55]is accompanied for many days by the smaller albatross,
[00:34.82]which may keep company with the vessel for an hour
[00:37.76]without visible or more than occasional movement of wing.
[00:42.57]The currents of air that the walls of the ship direct upwards,
[00:46.67]as well as in the line of its course,
[00:49.21]are enough to give the great bird with its immense wings
[00:52.62]sufficient sustenance and progress.
[00:55.93]The albatross is the king of the gliders,
[00:59.41]the class of fliers which harness the air to their purpose,
[01:03.44]but must yield to its opposition.
[01:06.54]In the contrary school, the duck is supreme.
[01:10.93]It comes nearer to the engines with which man has 'conquered' the air, as he boasts.
[01:16.66]Duck, and like them the pigeons, are endowed with steel-like muscles,
[01:22.40]that are a good part of the weight of the bird,
[01:25.53]and these will ply the short wings with such irresistible power
[01:30.00]that they can bore for long distances through an opposing gale
[01:34.28]before exhaustion follows.
[01:37.28]Their humbler followers, such as partridges,
[01:40.62]have a like power of strong propulsion, but soon tire.
[01:45.26]You may pick them up in utter exhaustion,
[01:47.95]if wind over the sea has driven them to a long journey.
[01:52.51]The swallow shares the virtues of both schools in highest measure.
[01:56.72]It tires not, nor does it boast of its power; but belongs to the air
[02:02.68]travelling it may be six thousand miles to and from its northern nesting home,
[02:08.63]feeding its flown young as it flies, and slipping through a medium
[02:13.50]that seems to help its passage even when the wind is adverse.
[02:18.31]Such birds do us good,
[02:20.45]though we no longer take omens from their flight on this side and that;
[02:24.93]and even the most superstitious villagers
[02:27.34]no longer take off their hats to the magpie and wish it good-morning.