Four years in college is the best time in life for many people. However, in these four years, there will always be some regrettable things. Here are some things that may be regrettable:

1. Didn't make full use of time: four years in college seems to be a long time, but in fact it passes quickly. Many people may regret not making better use of this time to learn more knowledge, participate in more activities and make more friends.

2. Didn't seize the internship and job opportunities: During my college years, there were many internship and job opportunities. Some people may miss these opportunities for various reasons, which will lead to more competitive pressure when they look for a job after graduation.

3. Don't join clubs and organizations: There are various clubs and organizations in universities, which allow students to develop their hobbies and exercise their abilities after studying. Some people may regret not participating in these activities.

4. I didn't cherish the time with my classmates and teachers: after four years in college, we will meet many interesting classmates and excellent teachers. Some people may feel sorry for not cherishing the time with them.

5. Not learning to live independently: For many students who just entered the university, living independently may be a challenge. Some people may feel sorry for not learning to live independently.

6. Failure to develop good study and living habits: It is very important to develop good study and living habits during college. Some people may feel sorry for not forming these habits.