Trees make our life better in many ways.As trees need CO₂ when they （1）

grow

grow

/gr??/，they take in CO₂ so that there will be less of it in the air.Also，trees can give off O₂，which is （2）

necessary

necessary

/nes?s?r?/for all living things on the earth.
    Trees and forests play an important part in（3）

helping

helping

（help） to improve our environment.They can stop the soil （4）

from

from

being washed away.They can make water better and the air （5）

cleaner

cleaner

（clean）.At the same time，forests are the home of many （6）

animals

animals

，such as tigers，elephants，monkeys and so on.
    However，forests all over the world are becoming fewer and fewer.People cut down trees to make paper，build houses or do other things.Every minute，between 50 and 100 acres（英畝） of forests are （7）

destroyed

destroyed

（destroy）.If this goes on，there will be no forests left in one hundred years.
    Luckily，many countries have come to realize the （8）

importance

importance

（important） of forests.They pass laws to （9）

protect

protect

/pr?'tekt/ the forests.For example，in some countries， （10）

if

if

people cut down one tree，they will plant another tree or more trees.