"The second is a unit of time defined as the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom. The second is a base unit in the International System of Units." . "The second is a unit of time defined as the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom."@en . "s" . . "\u79D2"@zh . "seconde"@nl . . "sec" . . "second"@en . .