Excuse me, do you want to ask "why can't Dr. Zhang's physical examination pocket classroom app be screened after upgrading?" The reasons why this app can't take screenshots are as follows:

1. Prevent content from being stolen: Some educational applications contain copyrighted textbooks, test questions or other sensitive information. Banning screen capture can prevent users from intercepting these contents and sharing them with others, thus protecting intellectual property rights.

2. Prevent cheating: Some online education platforms will provide online exams or tests. Banning screen shots can reduce the possibility of cheating. If students take screenshots, they will send screenshots of questions or answers to others, undermining the fairness of the exam.

3. Privacy protection: In some cases, educational applications contain sensitive personal information, such as students' names, grades or other personal data. Banning screen capture can prevent this information from being improperly used or leaked.