This paper purposes to solve the tricky problems with scope readings by applying May`s (1985) Path Containment Condition (PCC) and Chomsky`s (2000) Phase Impenetrability Condition (PIC) to sentences involving quantifiers and wh-phrases. Contradictory discussions have ensued in connection with scope readings. This paper shows how such problems can be solved with the application of the concept of path and phase presented by May and Chomsky. In order to verify that the PCC and PIC are crucial to the reading of scope ambiguity, this paper covers not only the sentences involving double object predicates and quantifiers, which have been regarded as a more tricky issue, but also other sentences containing complementizers and quantifiers. By employing the notion of path and phase in a unified way, this paper shows that m-command, not c-command, should be employed in deciding scope and its readings.