expose vs refrain

expose

verb
  • To submit to an active (mostly dangerous) substance like an allergen, ozone, nicotine, solvent, or to any other stress, in order to test the reaction, resistance, etc. 

  • To make available to other parts of a program, or to other programs. 

  • To abandon, especially an unwanted baby in the wilderness. 

  • To reveal, uncover, make visible, bring to light, introduce (to). 

  • To subject photographic film to light thereby recording an image. 

refrain

noun
  • The chorus or burden of a song repeated at the end of each verse or stanza. 

  • A much repeated comment, complaint, or saying. 

verb
  • To stop oneself from some action or interference; to abstain. 

  • To abstain from (food or drink). 

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