Subject	black soot
Predicate	be formed
Object	when the flame is luminous
Modality	Modality Occurrences
Polarity	POSITIVE
Plausibility	0.3076
Neighborhood Sigma	0.3901
Local Sigma	1.0000
Example Sentences	Sentence Occurrences Source black soot is formed when the flame is luminous 1 Answers.com Questions