Birds don't fly high up in the sky. 鳥不會飛的很高。
The air is too thin. It is hard for birds to breathe in thin air .
空氣太稀薄了。鳥類在稀薄的空氣中很難呼吸。
Thin air doesn't hold them up. 稀薄的空氣支撐不了它們。
Birds fly near the ground so that they can see where they are.
鳥飛得離地面很近,以便它們能看到自己在哪里。
The birds look for places they know. Then they do not get lost.
鳥兒尋找他們知道的地方,這樣它們就不會迷路。
Some birds fly so low over the ocean that the waves often hide them.
有些鳥在海面上飛得很低,海浪常常把它們遮住。
Many birds fly long distances in the spring and autumn.
許多鳥在春天和秋天飛得很遠(yuǎn)。