sentence1: to extract opinion targets , many studies regarded opinion words as strong indicators ( cite-p-16-1-3 , cite-p-16-1-16 , cite-p-16-1-10 , cite-p-16-1-18 , cite-p-16-3-5 ) .
sentence2: in unsupervised methods , most approaches regarded opinion words as the important indicators for opinion targets ( cite-p-16-1-3 , cite-p-16-3-2 , cite-p-16-1-18 , cite-p-16-3-5 ) .