单项选择题
Questions 18 to 20 are based on the following passage. At the end of the passage, you will be given 15 seconds to answer the questions. Now, listen to the passage.
A. one B. two C. five D. seven
A. He’s taking a break from studying. B. He has already finished studying. C. He was assigned to watch a program by his professor. D. He’s finding out some information for a friend.
A. 7 hours. B. 8 hours. C. 17 hours. D. Several hours.