pencil in vs uncover

pencil in

verb
  • to provisionally schedule 

  • to fill in or write in using pencil 

uncover

verb
  • To remove one's hat or cap as a mark of respect. 

  • To reveal the identity of. 

  • To expose the genitalia. 

  • To remove a cover from. 

  • To show openly; to disclose; to reveal. 

  • To expose (lines of formation of troops) successively by the wheeling to right or left of the lines in front. 

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