Subject	isotope
Predicate	has_property
Object	difficult to separate by chemical methods
Modality	Modality Occurrences
Polarity	POSITIVE
Plausibility	0.9145
Neighborhood Sigma	0.9150
Local Sigma	1.0000
Example Sentences	Sentence Occurrences Source isotopes are difficult to separate by chemical methods 2 Google Autocomplete, Answers.com Questions