一旦所有人都登上了飞机，门就关上了。

Once everyone was ___aboard the plane, the doors were closed.

飞机上的食物曾经很棒，但现在已经变差了。

The food ___aboard the aircraft used to be excellent, but it has declined.

出发前请确保所有乘客都登上了巴士。

Please make sure all passengers are ___aboard the bus before departure.