rack one's brain

rack one's brain  {v. phr.}
To try your best to think; make a great mental effort; especially: to try to remember something you have known.
Bob racked his brain trying to remember where he left the book.
Susan racked her brain trying to guess whom the valentine came from.
John racked his brain during the test trying to solve the problem.
Categories: {v. phr.}

'rack one's brain' on video