1.Aircraft manufacturer Boeing has grounded the entire global fleet of its 737 Max aircraft.
ground 使停飞
The civil aviation minister ordered all the planes to be grounded.
该民航部长命令所有飞机不得起飞 。
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.
可能难以查明事实真相 。