Definition
To do something quickly and often while doing something else, without prior preparation or much thought about how it should be done.
張口就來
We decided to change the presentation flow on the fly during the meeting.
我們在會議期間臨時決定改變簡報流程。
Due to the time crunch, I had to finish the report on the fly on the plane.
由於時間緊迫，我不得不在飛機上臨時完成報告。
Many decisions for this project were made on the fly during execution.
這個專案的許多決定都是在執行過程中臨時做出的。
To perform a function without interrupting a computer program that is currently running.
即時（電腦程式）
This software can adjust graphics settings on the fly while the program is running.
這個軟體可以在程式運行時即時調整圖形設定。
The engineer developed a tool that allows the program to update data on the fly without restarting.
工程師開發了一個工具，可以在不重新啟動的情況下即時更新程式數據。
The system can dynamically add server resources on the fly without stopping the service.
系統可以在不停止服務的情況下動態地即時添加伺服器資源。