Birds don't fly high up in the sky. The air is too thin. It is hard for birds to breathe in thin air. Thin air doesn't hold them up.
Birds fly near the ground so that they can see where they are. The birds look for places they know. Then they do not get lost. Some birds fly so low over the ocean that the waves often hide them. Many birds fly long distances in the spring and autumn.
air n. 空气
breathe v. 呼吸
hold v. 把握，支持
ground n. 地面
ocean n. 大海，海洋
wave n. 波，波浪
distance n. 距离；遥远
一、Read the passage and write "T" for true and "F" for false.
( ) 1. Thin air is hard for birds to breathe.
( ) 2. Thin air doesn't hold birds up, so they don't fly high up in the sky.
( ) 3. Birds fly near the ground to find food.
( ) 4. Sometimes wave can be higher than some birds.
( ) 5. Many birds fly long distances only in the spring and autumn.
二、According to the passage, choose the best answer:A, B, C or D.
( ) 1. Birds fly _______ .
A. on the clouds B. through the water
C. near the ground D. high in the sky
( ) 2. The thin air high up ______ .
A. makes breathing hard B. makes breathing easy
C. holds the birds up D. is just like the air near the ground
( ) 3. When the birds fly close to the water, the waves ______ .
A. hold the birds up B. may hide the birds
C. carry the birds along D. drown the birds
( ) 4. Birds fly near the ground in order to _______ .
A. look for food B. look for places they know
C. fly a long distance D. breathe fresh air
( ) 5. Which of the following is true?
A. Birds don't fly in summer and winter.
B. Birds always fly south.
C. Many birds fly long distances in the spring and autumn.
D. Birds can't fly high in the sky.