【单选题】听力原文:W: Could you tell me the time of the last plane to New York this evening? M: There's one at 9:20, but it's fully booked, I think. W: Then the time of the first plane tomorrow morning? M: The firs...
【单选题】If plane polarized light is sent through two polarizers, the first at 45° to the original plane of polarization and the second at 90° to the original plane of polarization, what fraction of the origin...