2. College students' minds have gradually matured, and they can appreciate the meaning of love in college and have the right to fall in love;
3. Puppy love refers to the establishment of love relationship between teenagers. The word "puppy love" is only widely used in Chinese mainland.
4. Twenty years' investigation in China shows that many people had feelings in middle school. Most of them are unrequited love and unrequited love. Only when we have a good impression on each other can we develop into puppy love;
5. Puppy love behavior is the practice of transforming psychology into behavior on the basis of teenagers' sexual and physical development.