Forests help to keep water from running away，so drought（干旱）doesn’t often happen．Chinese people have built a“Great Wall”of trees，millions of trees across the northern part of the country．

    The Great Green Wall 1 ________ （be）7,000 kilometres long，and it will stop the wind from 2 ________（blow）the earth away．It 3 ________already ________（save）a lot of land．

    Wang Feng is a worker at Yulin in Shanxi Province．He 4 ________ （work）on the Great Green Wall with many other people．We 5 ________ （visit）him at his workplace and when we saw him he 6 ________ （work）among the trees．He told us something about his work“We must 7 ________ （plant）many thousands of trees every year，”he said“You see all those small trees over there on that hill? That was sand five years ago．Now it's a young forest! In a few years’ time，we 8 ________（cover）those mountains with trees，too!”He pointed to the high mountains far away．

    Was it difficult 9 ________ （work）on the Great Green Wall?

    Yes，It’s hard work．but it's very important．The only problem is we have to 10 ________（grow）our own food．But thanks to the Great Green Wall，the land produces more crops．So the more trees there are，the better harvest we have．”

Thousands of trees are planted on ______ banks of the river．

1. A.
   every
2. B.
   both
3. C.
   any
4. D.
   each