Choe, Hyon Sook. 2000. Focus-sensitive Question and Copy Theory. Studies in Modern Grammar 19, 27-48. In this paper, adopting a version of Chomsky`s (1971) conception of focus/presupposition (cf. also Dryer 1996), I suggest that yes-no question and wh-question refer to the information of focus and that the extraction of yes-no and wh-question operators (that are lexically inserted on a focus) is involved in yes-no and wh-questions. I also suggest that the concept of focus is both LF- and PF-related and that extraction in yes-no question and wh-question refers to PF-related focus information while yes-no and wh-question operators are lexically inserted on an LF-related focus (a focus category, here) so that only focus categories (which are not presupposed) can be questioned. Based on the above suggestion, I reinterpret the copy theory introduced in Chomsky (1993) by suggesting a notion of selective deletion under an hypothesis that the information on LF- and PF-related focus is syntactically available in terms of formal feature. The hypothesis makes it possible to suggest a copy theory that employs selective deletion but not QR, which is conceptually and theoretically better than a copy theory discussed in Chomsky (1993) and assumed in Chomsky (1995, 1998, 1999).