It Ain't Necessarily So(From Porgy And Bess)2 并非必需 It ain't necessarily so from Porgy and Bess It Ain't Necessarily So (from Porgy and Bess) It ain't necessarlly so from Porgy and Bess It Ain't Necessarily So from Porgy and Bess It Ain't Necessarily So from Porgy and Bess; It Ain't Necessarilu So from Porgy and Bess 5 It ain't necessarily so from Porgy and Bess / George Gershwin