One day a policeman was taking a thief to the city police station. On their way they came to a shop where bread was sold. "We have no food. And we must eat something on the train." said the thief. "It's a long way to the city and it will take us much time to get there. I'll go into this shop and buy some bread. Then you and I can eat it on the train. Wait here for me." The policeman was glad, "I'll have some food on the train," he thought. "Be quick," he said to the thief. "We haven't much time." The thief went into the shop, and the policeman waited in the street for a long time. He began to worry. He thought about the train, and at last he went into the shop. "Where's that man who came in here to buy some bread?" asked the policeman. "Oh, he went out by the back door," said the shopkeeper. The policeman ran out but he could not see the thief. So he had to go back to his own station and tell the others about it. They were very angry with him, and he was very unhappy. All the police of the town began to look for the thief again, and they soon caught him. They brought him back to the police station and called the same policeman." "Now," said the officer, "take him to the city, and don't lose him again." The policeman and the thief left the station, and they came to the same shop. "Wait here," said the thief. "I want to go into that shop and buy some bread." "Oh, no," said the policeman. "You did that once, and ran away. This time, I'll go into the shop and buy the bread, and you must wait here for me."

The policeman was asked to ______.

A.look for the thief

B.buy some bread

C.bring the thief to railway station

D.take the thief to the city police station