看绝望的主妇学商务短语：Be in full swing

Be in full swing：at a stage when the level of activity is at its highest; operating fully or has already been happening for some time, rather than being in its early stages.  （处于事情运行的高潮阶段或事物运行全部展开的阶段）

The party was in full swing, and everyone was waiting to surprise the guest of honor. Little did they know, an even bigger surprise was on its way. （DH S05E05 25:49）

参考翻译：聚会正进行到高潮部分，大家都在等待宾客的神秘惊喜，但没人知道 一个更大的惊喜正在靠近。