九年级英语The Great Green Wall课件2.ppt

The Great Green Wall
Lesson 42 Unit 11 Book 3
Ask and answer
How can forests prevent floods?
Why is the Great Green Wall so important?
The trees can keep the rain drops from hitting the soil directly, so the soil is not easily washed away. The dead leaves on the ground also keep the water from running away. The water then stays in on place and is used by the trees in the forest.
Because it will stop the wind from blowing the earth away.
What do we have to do to prevent the sand- storms , or the floods or the droughts from happening ?
We must build more Great Green Walls .
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Revision
forest
drop
drought
soil
flood
sand
directly
leaf
leaves
wide
widely
towards
among
prevent
hear of
run away
point to
farmland
blow
blew
blown
far away
Useful Expressions
流失,逃跑
run away
wash away
冲走
落叶
dead leaves (leaf)
用这种方式/方法
in this way
越多越好,多多益善
The more, the better
被……覆盖
be covered with
装满
be filled with
(= be full of )
在几年里
in a few years’ time
指向
point to
= point at
很远,遥远
far away
由于,多亏
thanks to
阻止……做某事
Keep … from doing sth.
= stop …(from) doing sth.
= prevent …(from) doing sth.