?? ??????????????????
????:1??????????:??????
2???sn??
3??????????
4???????300???
5?????????????
?? ? ???????? ?
????????C919????
?????C919???? ?????????
??????????????? 1/59??28???,?????,??????????????????OD634?????11????????55??,?OD634??????????????????,???????????????,??3??????????????????15???????????????,?????,4??30??,??????????????????“????????”??=?,??
???????????????:????????????????????
???? ??