Birds can fly because they have wings. 鸟儿因为有翅膀才能飞。

　　Each bird has differently shaped wings. 每种鸟的翅膀的形状都不同。

　　How fast do birds fly? 鸟能飞得多快呢？

　　The speed of birds varies. 它们的速度各不相同。

　　Pigeons fly at a rate of about 35 to 60 miles per hour. 鸽子的飞行速度约35-60英里（约56.3-96.7千米）每小时

　　And hawks at a rate of about 180 miles per hour. 而鹰的飞行速度约180英里（约289.7千米）每小时。

　　However, there are some birds which can't fly at all. 然而，有些鸟儿根本就不能飞。

　　They are penguins and ostriches. 它们就是企鹅和鸵鸟。