英语高手快进把…… 能不能帮我分析一下下面这个句子。

本句中to the entertainment of the onlookers表示 He fell into the water的结果，是结果状语。
much表示程度修饰介词短语to the entertainment of the onlookers。

这种结构相当常见，句中放在句首更常见。To my great relief/Much to my relief, I wasn't late. 我最庆幸的是没有迟到.
Much to his chagrin, he did not win the game. 使他非常懊恼的是，他在比赛中未能取胜。
Much to his surprise, Ted won first prize in the raffle. 使他大吃一惊的是，特德在抽彩中得了头奖。
My husband himself gave me an opportunity to ease myself of the secret, much to my satisfaction. 我丈夫给我一个机会来解脱我心中的秘密，使我感到很愉快。

他跌进水中，旁观者大乐