Many researchers have developed several algorithms for this purpose and generated large static lexicons of words marked with prior polarities (Hatzivassiloglou and McKeown, 1997;Turney et al., 2003;Esuli, 2008;Mohammad et al., 2009;Velikovich et al., 2010).
there exist some polarity-ambiguous words, which can dynamically reflect different polarities along with different contexts.