Having been teaching hundreds of students over the past years, I have to admit that sometimes I do have a hard time knowing everyone's name by heart. It 's kinda like an embarrassment when someone shows up in my class after a long break, expecting me to call his or her name up immediately. Such a thing does happen to anyone of us at all times. It occurred to me that there is a good sentence to use in this case.
"I am very sorry, but your name eludes me."
You can also use "elude" for other situation.
"It eludes me that he has borrowed five grand from me before."
to know something by heart 記住某事
it occurred to me 我突然想起
something eludes me 我忘記某事