[填空题]
The ripples in a certain groove 10.8 cm fro usf6fr- ,aa9 .k7;blejgmo l5mlbl5,fid a5+up7z1dde .u y*g the center of a 33-rpm phonograph record have a wavelength of 1.70 mm. What will be b e*ziy,51 d+d7d.p lu5fualgthe frequency of the sound emitted? Hz