The day we visted, officers were talking about an incident that had occurred just that morning: a heavy water-bag had been dropped from the fifth tier of the cellblock down onto another inmate.
长官说起我们去的那天早上发生的一个事件：一个很重的水袋从5层的牢房走廊扔下砸到另一个犯人。
2
A plastic bag was floating in the water.
一个塑料袋在水中漂浮。
《牛津词典》
3
It pumps water out of tiny bag-like bladders, making a vacuum inside.