The European settlers moved to Africa a hundred years ago. Often they took land away from the Africans and set up farms at that time. Then they would hire the Africans to work on the farms at low wages. The best farms were in the White Highlands. That was where the wheat, coffee and corn were grown. Let us visit a farm belonging to Mr. Brown, a European settler a century ago.
If you are an African, you must change your clothes before you go. Put on dirty old clothes, the more ragged（衣衫褴褛）the better. Mr. Brown knows educated Africans by the way they dress. He does not allow these people to visit his farm. He says they are lazy and they have strange ideas that his workers do not need to know. In fact, he is afraid the outsiders will notice some things.
When you look around his big farm, you wonder where his workers live. All you see are some mud huts（窝棚）, which you might think are for animals. A wire fence and a big ditch（沟）surround these huts. Mr. Brown has told his workers that the fence and ditch are necessary to keep thieves away. But Mr. Brown's own house has no fence and ditch. You might think that Mr. Brown just wanted to fence in his workers.
The farm is very large and rich. It has many good fat sheep, cows and pigs. But the workers are thin and hungry-looking. They all have dirty, ragged clothes. Yet they are very friendly and will take you to their homes. The hut is their kitchen dining room, bedroom and bathroom. Everyone in the family sleeps there. The children all sleep on the floor with the sheep. You might not have dreamed that people can live so miserably.
Mr. Brown built the fence and ditch to_____.