我懊恼地发现我把包落下了。

I was annoyed to discover that I'd left my bag ___behind.

派对结束后，几个人留下来帮忙清理。

After the party a few people stayed ___behind to help clear up.

公交车司机告诉他，一个手提箱被落下了，因为没有人认领。

The bus driver told him that a suitcase was left ___behind because nobody claimed it.