upon

The king placed the royal golden crown upon the young prince's head.

(Chinese) 国王将金色的王冠戴在了年轻王子的头上。

He sat upon a large rock and watched the sun set over the distant mountains.

(Chinese) 他坐在一块大石头上，看着夕阳落在远处的山峦后面。

Upon arriving at the airport, she realized she had forgotten her passport at home.

(Chinese) 一到达机场，她就发现自己把护照忘在家里了。

The contract will be signed upon the successful completion of the legal review.

(Chinese) 合同将在法律审查成功完成后立即签署。