（事件）正在进行中，处于活跃状态
If an event is in full swing, it has already been happening for a period of time and there is a lot of activity.
The party was in full swing by the time we arrived. 我们到达时聚会正是高潮。
The International Film Festival was in full swing when we arrived.
Cinco De Mayo festivities are currently in full swing.
If you arrive when the carnival is in full swing, all the hotels will be booked.
Preparations for the conference are now in full swing.
Wedding preparations are in full swing and it will be a busy couple of months.
See also: full adjective (COMPLETE)