For a sentence s containing such a collocation c, since the in-sentence features are always ambiguous, it is difficult to disambiguate the polarity of c by using them.
some previous work turned to investigate its surrounding contexts' polarities (such as the sentences before or after s), and then assigned the majority polarity to the collocation c (Hatzivassiloglou and McKeown, 1997;Hu and Liu, 2004;Kanayama and Nasukawa, 2006).