短文改错,一行一错,如多一个词；缺一个词；错一个词；没有错.

短文改错,一行一错,如多一个词；缺一个词；错一个词；没有错.
In 1620,about half the USA was cover by forests. 1.( )
today the forests have almost gone . A lot of good land 2.( )
has gone with it , leaving only sand . China does not 3.( )
want to copy the USA example .We`re planting more 4.( )
and more tree . We`ve built the "Great Grean Wall" 5.( )
of trees across north part of our country . The Great 6.( )
Grean Wall is among 400 and 1,700 killometres wide. 7.( )
It will stop the wind from blow the earth away . More 8.( )
"Great Green Walls" are be needed . Trees must be 9.( )
grown all over the world . They`ll make world better. 10.( )