飞机就要起飞了。

The plane is about to take off.

《新英汉大辞典》

她知道五分钟后飞机就要起飞了。

She knew the plane was taking off in five minutes.

youdao

飞机就要起飞了，可我却忘了带机票。

The plane is about to take off, and yet I left my ticket behind.

youdao

And she has to catch a flight, and you know the flight is going to leave in three hours and she's taking her time.

她马上得去赶飞机，你知道飞机在三个小时后就要起飞了。可她还在磨磨蹭蹭。

Make sure 课堂 - SpeakingMax英语口语达人