1.Aircraft manufacturer Boeing has grounded the entire global fleet of its 737 Max aircraft.
ground 使停飛
The civil aviation minister ordered all the planes to be grounded.
該民航部長命令所有飛機不得起飛 。
2.and will study the data in them to ascertain the reason for the aircraft falling from the sky.
ascertain 查明
It can be difficult to ascertain the facts.
可能難以查明事實真相 。