A、Athletic and recreational. B、Food and transportation. C、Bookstore and post office. D、Medical and audio-visual. B文中详细通知了interca

During the summer session there will be a revised schedule of services for the university community. Specific changes for intercampus bus services, summer hours for the cafeteria and recreational and athletic facilities will be posted on the bulletin board outside the cafeteria. Weekly movie and concert schedules which are in the process of being arranged will be posted each Wednesday outside the cafeteria. Intercampus buses will leave the main hall every hour on the half hour and make all of the regular stops on their route around campus. The cafeteria will serve breakfast, lunch, and early dinner from 7 a.m. to 7 p.m. during the week and from noon to 7 p.m. on weekends. The library will maintain regular hours during the week, but shorter hours on Saturdays and Sundays. The weekend hours are from noon to 7 p.m.
    All students who want to use the library borrowing services and recreational athletic, and entertainment facilities must have a valid summer identification card. This announcement will also appear in the next issue of the student newspaper.
19. Which of the following is the main purpose of this announcement?
20. Specific schedule revisions for which of the following facilities are listed in this announcement?
21. According to the announcement, which of the following is true of special summer hours for the library?
22. According to the announcement, when is a validated identification card needed?