Lesson 15-the riddle of time I. Warm-up Questions Think about it For your reference A mechanical watch does not work What are the possible reasons for it? W BTL E To be continued on the next page.Lesson 15—The Riddle of Time W B T L E I. Warm-up Questions To be continued on the next page. A mechanical watch does not work. What are the possible reasons for it? Think about it For your reference