Bird flight 1 鸟的飞行方法

No two sorts of birds practise quite the same sort of flight; the varieties are infinite; but two classes may be roughly seen. Any ship that crosses the Pacific is accompanied for many days by the smaller albatross, Which may keep company with the vessel for an hour without visible or more than occasional movement of wing. The currents of air that the walls of the ship direct upwards, as well as in the line of its course, are enough to give the great bird with its immense wings sufficient sustenance and progress. The albatross is the king of the gliders, the class of fliers which harness the air to their purpose, but must yield to its opposition.
没有任何两种鸟的飞行方式是相同的。鸟的飞行方式千差万别，但大体上可分为两类。任何一艘横度太平洋的轮船都会有一种小信天翁伴随飞行许多天。它们随船飞行一小时也难得见其扇动一下翅膀。沿船体的上升的气流和沿航线向前的气流给这种巨翼大鸟以足够的浮力和推力。信天翁是滑翔飞行的鸟类之王，它能自如地驾驭空气，但必须顺气流飞行。

New words and expressions 生词和短语

albatross
n. 信天翁
sustenance
n. 支撑力
glider
n. 滑翔者
harness
v. 利用