【正确答案】 B

【答案解析】[解析] 17-20
This event takes place on Tuesday, May 13, from 6:30 p.m. to 9 p.m. The theme for the evening is "Heal the World" and students are encouraged to dress in line with this. Tickets go on sale next week and there is a limited number. The cost is $3 for those dressed in theme, and $5 for others. There will be no door sales on the night even if all tickets are not sold. Last year tickets were sold out so students need to get in early to be sure of getting a ticket.
Students must arrive by 7:00 p.m. and will be required to remain in the hall until the end. Anyone who wishes to leave early needs to provide written permission from his or her parents. Cookies will be for sale during the social and drinks will also be available for free. Students may not bring their own drinks or food. Students who have shown a high level of cooperation or whose attendance has been very good so far this year are welcome to attend. Students who are not meeting the required standard have been told that they risk not being allowed to attend if there are any further behavior problems.