1. The author of this book is my alumnus from high school.2. When I graduated from college, I hoped I would keep in touch with all my alumni.
 alumni alumnus校友 = alumni (複數) = alumnus (單數)
你剛剛說了甚麼? 不好意思，我放空了一下。 (請填空)
What did you just say? I am sorry. I just lost my trai of thought.