In the past, engines represented a significant Achilles' heel in China's aviation sector. However, this long - standing problem has now been effectively addressed in both military and civilian aviation realms. Aerospace engines are often regarded as the pinnacle of modern industrial achievement, serving as a crucial yardstick for measuring a nation's industrial might. China's AECC (Aero Engine Corporation of China) Group has remained steadfast in its pursuit of independent innovation, steering the development of aviation power towards high - end, intelligent, and eco - friendly directions.

### Explanation of optimizations - **Title**: - “independently developed” is changed to “Self - Developed”. “Self - Developed” is a more commonly used and natural - sounding phrase in English when referring to a country's own development efforts. - “makes its debut” is changed to “Makes Its Grand Debut”. The addition of “Grand” adds a sense of importance and significance to the event, which is appropriate for the launch of a new engine. - “to be used in” is changed to “Set to Power”. “Set to Power” is more dynamic and implies that the engine is ready and destined to drive the C929 aircraft, rather than just being a passive component to be used. - **Paragraph**: - “a weak point” is changed to “a significant Achilles' heel”. “Achilles' heel” is a well - known English idiom that conveys a vulnerable or weak spot in a more vivid and expressive way. The addition of “significant” emphasizes the importance of this weakness in the past. - “this issue has been resolved” is changed to “this long - standing problem has now been effectively addressed”. “Long - standing” gives a sense of the duration of the problem, and “effectively addressed” is a more formal and precise way of saying that the problem has been solved. - “the crown jewel of modern industry” is retained but the following part is adjusted for better flow. “serve as an important indicator” is changed to “serving as a crucial yardstick”. “Crucial yardstick” is a more vivid and common expression in English for measuring something, in this case, a country's industrial prowess. - “adheres to independent innovation” is changed to “has remained steadfast in its pursuit of independent innovation”. “Remained steadfast in its pursuit” is a more elaborate and formal way of expressing the commitment to independent innovation. - “driving the development” is changed to “steering the development”. “Steering” gives a more active and directional sense, as if the AECC Group is guiding the development of aviation power in a specific and purposeful way. - “high - end, intelligent, and green directions” is adjusted to “high - end, intelligent, and eco - friendly directions”. “Eco - friendly” is a more commonly used and well - understood term in English compared to “green” in this context, as it specifically refers to being environmentally friendly.