[originaltext] Mrs. Jones was very fond of singing. She had a very good voic

Mrs. Jones was very fond of singing. She had a very good voice, except that some of her high notes tended to sound like a gate which someone had forgotten to oil. Mrs. Jones was very conscious of this weakness, and took every opportunity she could find to practice these high notes. As she lived in a small house, where she could not practice without disturbing the rest of the family, she usually went for long walks along the country roads whenever she had time, and practiced her high notes there. Whenever she heard a car or a person coming along the road, she stopped and waited until she could no longer be heard before she started practicing again, because she was a shy person, and because she was sensitive about those high notes. One afternoon, however, a fast open car came behind her so silently that she did not hear it until it was only a few yards away from her. She was singing some of her highest and most difficult notes at the time. As the car passed her, she saw an anxious expression suddenly come over its driver’s face. He put his brakes on violently, and as soon as the car stopped, he jumped out and began to examine his tires carefully. Mrs. Jones dared not tell him what the noise he had heard had really been, so he got back into his car and drove off, as puzzled as he had been when he stopped.
Questions 16 to 18 are based on the passage you have just heard.
16. What did Mrs. Jones often practice?
17. Why did the driver stop the car?
18. Where did the noise come from?