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 To Americans, promises to meet the deadlines and appointments are taken very seriously because ______.
A．They believe that time should be planned and future events fitted into a schedule B．They dwell too much on the past C．They recognize the present rests on the past D．They have developed their sense of depth of time