If the event is just 2 hours long, keep the intro and the closing short. If you spend 2.5 hours or more, you can spend more time on the closing. If the event is even longer, consider running something by the middle of it, to give people a moment to step away from the project.
如果活动市场只有两个小时，请保持介绍和谢幕简短。如果您花费超过2.5个小时，您可以用更久的时间收尾。如果活动时间更长，请考虑在中间加入一些内容，给予人一些从项目中间离开的时间。