Directions: In this section, you will hear three short passages. At the end of each passage, you will hear three or four questions. Both the passage and the questions will be spoken only once. After you hear a question, you must choose the best answer f r om the four choices marked A) B) C)and D). Then mark the corresponding letter on Answer Sheet I with a single line through the center . Passage One Questions 16 to 18 are based on the passage you have just heard. [音频]