The boy fell and scraped the skin off his knee.

这男孩摔了一跤, 擦破了膝盖上的皮。

I barked my shin on a tree stump.

我磕到了树桩上，胫部擦破了皮。

He boohooed when he skinned his knee.

当他的膝盖擦破时, 他大声哭了起来。

Jack skinned his knee when he fell.

杰克跌倒时膝盖擦破了皮。

The bullet merely creased his shoulder.

子弹只不过擦破了他肩部的皮肤。

He skinned his knees when fell.

他摔倒时擦破了膝部的皮肤。