英语完形More than three hundred years ago,about half of the USA'

英语完形More than three hundred years ago,about half of the USA's land was covered by forest.
More than three hundred years ago,about half of the USA's land was covered by forest.But now the forests are almost 1 They can't stop good land from being sold.Today too many trees are being cut 2 in the USA.China doesn't want to follow the USA's 3 So China has built a new Great Wall of trees.It will stop the 4 from blowing earth away and stop the sand from moving towards the rich farmland.It has 5 saved a lot of land.We must plant 6 trees every year.The more,the better.
( ) 1.A.went B.changed C.gone D.covered
( ) 2.A.off B.down C.away D.for
( ) 3.A.forests B.land C.people D.example
( ) 4.A.wind B.sand C.rain D.cloud
( ) 5.A.still B.always C.already D.almost
( ) 6.A.fever B.much C.many D.more