Sentence:  The solitary, lumbering trolls of Scandinavian mythology would <WSD>sometimes</WSD> be turned to stone by exposure to sunlight. Barack Obama is hoping that several measures announced on June 4th will have a similarly paralysing effect on their modern incarnation, the patent troll. 
Meaning of the word marked with <WSD> tags:  On certain occasions, or in certain circumstances, but not always. (from 16th c.)