我看到一群鸟从窗前飞过。

I saw a flock of birds ___passing by the window.

我们静静哀悼这位伟大领导人的逝世。

We quietly mourned the ___passing of this great leader.

那只是一次短暂的相遇，之后再也没见过他。

It was just a ___passing encounter, and I never saw him again.

他通过了期末考试，感到非常高兴。

He was very happy about ___passing the final exam.

她把钥匙递给我时不小心掉在了地上。

She dropped the keys while ___passing them to me.