Zero Cond (scientific fact): if present+present
1st cond (possible): If present+future (will+present)
2nd cond (hypotetic): If past simple+ would+inf.
3rd (impossible): If past perfect+cond. Perfect (would have+3a)
Passive: open -> is/are opened // is opening -> is being opened // has opened-> has been opened// opened -> was/were opened // was opening-> was being opened // Had opened -> had been opened// is going to open-> is going to be opened// will open-> will be opened // will have opened-> will have been eaten.