But for some languages, collecting parallel corpora is not easy.
many researchers paid attention to bilingual dictionary extraction from comparable corpora (Fung, 2000;Chiao and Zweigenbaum, 2002;Daille and Morin, 2008;Robitaille et al., 2006;Morin et al., 2007;Otero, 2008), in which texts are not exact translation of each other but share common features.