简答题：You have made an appointment with Prof. Wang, but failed to

You have made an appointment with Prof. Wang, but failed to keep it. Write a letter to
him. Your letter should include:
1)apologize for your failure to keep the appointment
2)explain your reason to your teacher
3)express your wish to make another appointment
You should write approximately 100 words. Do not sign your name at the end of your letter.
Use "Li Ming" instead. You do not need to write the address.