For more than four years, the final moments of China Eastern Flight 5735 remained shrouded in secrecy, with few clues to a baffling descent from 29,000 feet that left no survivors. 四年多来，中国东方航空5735号航班的最后时刻始终笼罩在重重迷雾中，外界几乎找不到任何线索，能够解释这架飞机为何会从约8840米高空突然急剧坠落，最终无人生还。…