Potential rare, and tough predicates yasui \u27easy\u27, nikui \u27hard\u27 pose some important questions for most grammatical theories. They are attached to another predicate and change the number of its complements. They may turn an adverb into a ga-marked complement. They may delete the original subject and promote a complement into the subject position. This paper gives syntactic analysis of some typical expressions that contain potential rare, and formulates semantic representations of them. The syntactic analysis follows that of Muraki (1993) in the framework of phrase structure grammar (Cf Gazdar et al 1985,Gunji 1987). The semantic representations are based on Montague semantics (Cf Montague 1973,Dowty 1981) with some adjustments
