they can be opinion words (see Sentences 1-3), communication words, such as maintained in Sentence 2, or other lexical cues, such as according in Sentence 3.
all sources used for this type of generalization are known to be predictive for opinion holder classification (Choi et al., 2005;Kim and Hovy, 2005;Choi et al., 2006;Kim and Hovy, 2006;Bloom et al., 2007).