题目内容：
How did the dog perform his duties?A. He had few opportunities to do them.
B. He was delighted to show them off.
C. He did them quickly to get them over.
D. He did his best but was not often successful.
17. What does the passage tell us about gun dogs?
A. They are the fastest runners of all dogs.
B. Their teeth are removed when they are young.
C. They breed well, producing many young dogs.
D. They can carry birds, etc. without hurting them.
18. As a result of Williams’ work _________.
A. he did not get enough sleep
B. the dog grew accustomed to travelling by train
C. there was an oily smell from his clothes
D. the dog was confused about the time of the day
19. It upset Williams’ wife and family when _________.
A. Williams had to go to work at night
B. Williams made them all get up early
C. the dog made too much noise in the house
D. the dog would not let them see the newspaper
20. Williams did not realise his loss for several days because _________.
A. he trusted the dog to find the wallet
B. he had no occasion to feel in his pockets
C. he thought the wallet was in the house
D. he was unconscious all that time
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