I would be grateful if someonce can correct my mistake.

Thank you so much!
QA as bleow:
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Q:
You have been invited to attend an interview for a place studying course in a college. Unfortunately because of a previous appointment you cannot come at the time they wish.
Write a letter to the admissions tutor and explain your position. Apologise and offer to come on another day or later the same day. Ask also how long the interview will be and whether there will be any tests during it.
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A:
Dear Sir,
Thank you for giving me an opportunity for the interview of a place studying course in the college. However, I am not able to attend since I have a previous appointment with my family doctor on the next Saturday.
I had to be hospitalized last month due to high viral fever. After I fully recover, my family doctor suggest me to take a body check on the coming Saturday to ensure there are no virus inside my body anymore. That's the reason I couldn't attend the interview. I would like to ask if I can come on another day after the coming Saturday, also would you please let me know how long the interview will take and whether there will be any tests during it.
Thank you so much for your understanding.
Rdgs
Assman