【正确答案】In airjet spinning processing, sliver is fed into the draft system, then, the drafted fiber strand output from the nip of front rollers passes two nozzles. The fiber strand rotates due to the vortex of air stream injected into the nozzle at an adjustable pressure, by which, the resultant yarn with false twist and wrapped fibers is formed. In the first nozzle, the edge fibers of strand wrap the false twisted core by the air vortex produced by first nozzle itself. In the second nozzle, the air stream rotates in the opposite direction of the first nozzle, inserts the false twist into the strand and makes the edge fiber wrapped on the strand more tightly, which gives the yarn strength. The pressure employed in the second nozzle is usual higher than that in the first nozzle so that the core of strand is false twisted by the rotating caused by the air vortex in second nozzle.