What is a complex/difficult example of English tenses? [closed]

Theoretically, all 16 combinations of the following are possible:

  • active or passive voice
  • simple or perfective aspect (the latter formed using "have" + past participle)
  • simple or progressive aspect (the latter formed using "be" + present participle)
  • present or past

So, to speak of a past action which continued until a more recent past event happened: the task had been being worked on until something forced it to stop. So that's pluperfect passive progressive. (Pluperfect being another name for past perfect.)