For then there will be great suffering, such as has (gegonen | γέγονεν | perf act ind 3 sg) not been (gegonen | γέγονεν | perf act ind 3 sg) from the beginning of the world until now, and will (genētai | γένηται | aor mid subj 3 sg) never be (genētai | γένηται | aor mid subj 3 sg) again.
Reference
Matthew 24:21
Sequence
50