When we scratch, the action of our fingernails on the skin causes a low level pain signal that overrides the itching sensation.

当我们抓挠时，我们的指甲在皮肤上的动作会产生一种低水平的疼痛信号，这种信号会压倒瘙痒感。

He had lain in the uncomfortable position in which they had thrown him but for a few minutes when he became distinctly conscious of an acute itching sensation upon his hands, his neck and scalp.

他以他们把他扔到的那个不舒服的姿势躺了几分钟， 然后他清楚地意识到他的手、脖子和头皮上有一种剧烈的瘙痒感。