same ready prepare without amazing groups north fly mountains before

Birds are amazing animals，and their most（1）

amazing

amazing

skill is their sense of direction（方向）.Migrating（遷徙的） birds often（2）

fly

fly

thousands of kilometres.They find their way back to the（3）

same

same

place year after year.Even young birds seem to know which way to go.
    In Europe（歐洲），you may see big（4）

groups

groups

of birds.When the weather gets colder in autumn，they get（5）

ready

ready

to fly away to warmer countries.These birds fly south to Africa（非洲） for the winter.They will return（6）

north

north

to Europe next summer.
    Birds have many ways to（7）

prepare

prepare

for their migration journey.The little sedge warbler（蒲葦鶯） doubles（加倍） its weight by eating lots of insects（8）

before

before

it leaves Europe.It flies for 9，000 km.It travels（9）

without

without

stopping for four days to spend the winter in South Africa.Other birds，such as cranes（鶴），fly high over（10）

mountains

mountains

to spend the winter.