After a day of
swimming, John thought the blocked ear he had woken up the next morning was
simply water.
1. the next morning “次日早晨；第二天早晨”，之前不加冠词。表示时间意义的名词，如 day, afternoon, night, week, month, year 等，如果之前有this, that, one, all, any, each, every, (the) next, (the) last, the following 等词限定，在句中用作时间状语时，应省去相关的介词。
2. 从本句结构看， wake up 应为及物的短语动词，he had woken up the next morning 是 ear 的定语从句。
