????:1?????????:2021???????

2????????

3???????????

4?????????????

5??????

????????????????????“??”??????? ??? ??? ?????C919?????ARJ21???????????????? ??? ???? ?????C919???ARJ21????????????????? ????????????? ??? ?????“????????”????K-8???????????????????????? ? ?? ?????“?????”?K-8??????? ????? ?? ?C919??????? ???????????? ?????? ????? ?? ????? ????????????????????????? ??? ?????? ?????????????“????”???????????????? ? ? ??ARJ21??? ????? ? ???:??