The text describes Ken's bad day, which was full of mishaps and delays. The example sentence, "I was taking a shower when my mother called," sets the tone for the day's events. The subsequent points detail various incidents, including a neighbor's visit, a friend coming over for tea, an encounter with a policeman, and a bus delay due to rain, all culminating in Ken arriving late and upsetting Lizzy.
The "Nota bene" section explains that certain verbs (stative verbs like like, love, understand, see, hear, want, know, hate, think, have) are generally not used in continuous tenses. It provides examples of correct usage in simple tenses and contrasts it with possible (though less common) usage in continuous tenses for specific meanings (e.g., "I am thinking" vs. "I think").
Answer: Based on the events described, Ken's bad day was characterized by a series of unfortunate occurrences, including a late start due to a phone call during his shower, a neighbor's visit, a friend borrowing a book, an encounter with a policeman regarding a dog, a car breakdown, a bus delay due to rain, and ultimately arriving very late to Lizzy's, making her unhappy. He might have said something like, "I had a terrible day, everything went wrong!"