pass up vs retain

pass up

verb
  • To refuse (not accept); forgo. 

  • Used other than figuratively or idiomatically: see pass, up. 

  • To submit (hand in) items to a person, usually one's teacher. 

retain

verb
  • To hold back (a pupil) instead of allowing them to advance to the next class or year. 

  • To employ by paying a retainer. 

  • To keep in one's pay or service. 

  • To keep in possession or use. 

  • To hold secure. 

How often have the words pass up and retain occurred in a corpus of books? (source: Google Ngram Viewer )