在英语一般过去时态复习课上．李老师让学生描述自己周日的活动。男生Bob说：“I did my homework all day．I was tired．”李老师说：“Okay，sit down．Next student，please．”接下来的女生Selina说：“My father and I went to a bookshop last Sunday．Because he was a teacher now．”李老师微笑着问其他同学，“Selina的说法对吗 ”一个女同学站起来，回答说：“应该是：‘Her father is a teacher now．”’李老师又微笑地看着Selina。问：“Is she right ”Selina也笑了，改正了错误，说：“My father is a teacher．He and I went to a bookshop last Sunday．”李老师再一次会心地微笑。 问题：请结合教育学相关知识，对上述案例进行分析，请用中文回答。(10分)