apology

 Dear Professor [Name],

I am writing this letter to apologize for not attending the lab yesterday. I was really looking forward to the lab and completing the tasks assigned, but unfortunately, I was not feeling well. I woke up with a severe headache that persisted throughout the day, and I knew that I would not be able to give my best effort in the lab.

Additionally, I assumed that the lab would be cancelled or postponed because of your internal duty basis, as you had mentioned in the last class. However, I now realize that this was not a valid assumption on my part, and I should have confirmed the lab status before deciding not to attend.

I am truly sorry for any inconvenience or disruption that my absence may have caused to the lab and the other students. I understand the importance of attending all lab sessions and completing the assigned tasks, and I will make sure to catch up on the missed work as soon as possible.

Thank you for your understanding, and I hope to make up for my absence in the upcoming lab sessions.

Sincerely, [Your Name]