Subject	flashback
Predicate	has_property
Object	necessary
Modality	Modality Occurrences often 2 TBC[often necessary] 1
Polarity	POSITIVE
Plausibility	0.4079
Neighborhood Sigma	0.4576
Local Sigma	0.4079
Example Sentences	Sentence Occurrences Source flashbacks are often necessary 3 Google Autocomplete