1a : a slender opening or groove : slit, notch a mail slot in a very doorway b : a slim passage or enclosure c : a passage in the wing of an plane or of a missile that is situated commonly near the foremost edge and shaped in between a most important and an auxiliary airfoil for improving upon stream conditions above the wing so as to increase elev

????????????????????????????????????????????????????????????????????????????????????? ???????????????????????????????????????????????????????????????????????????????? ???????????????????????????????????????????????????? 138 ???????????????????????????????????????????? ????????????????????????????????????????????????? 750,000 ?? ??????????? ????????