:must, might (not), can't or could (not) + have+been 1.they recently found an ancient site in peru. it's almost 3000 years old and it (be) a religious site, but we can't be sure 2. i had my wallet an hour ago, but it's not here now. ) it in that shop! 3. sally hasn't called me. (not get ) my text message. 4. somebody (take) the book from her bag. or maybe she left it on the bus.