Dear Lee,
Excuse me for my long delay in returning to you your Understanding and Using English Grammar which I read through with great interest. I had finished reading the book and wa about to return it when a friend of mine came to see me.
Never having seen the book, he was so interested in it that I had to retain it longer.
However, I hope that in view of the additional delight thus afforded by your book, you will overlook my negligence in not returning it sooner. Thanking you for the loan.
Yours truly,
Jim
