past tense vs timing

past tense

noun
  • A grammatical form (often a verb form) that refers to an event, transaction, occurrence, or object that happened (or had happened), or existed, at some time before now (the applicable reference time). 

  • A grammatical form (often a verb form) that is used in a conditional expression to refer to an event, transaction, occurrence, or object that is hypothetical and often counterfactual. 

timing

noun
  • The time when something happens. 

  • The synchronization of the firing of the spark plugs in an internal combustion engine. 

  • The regulation of the pace of e.g. an athletic race, the speed of an engine, the delivery of a joke, or the occurrence of a series of events. 

  • An instance of recording the time of something. 

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