pain是不可数名词。
pain:n.(身体上的)疼痛;痛苦;苦恼;烦恼;
v.使痛苦;使苦恼
The pain was almost more than he could bear.
这种痛苦几乎使他无法忍受。
It was several weeks before he was completely free of pain.
过了几星期他的疼痛才完全消除。
This should help reduce the pain.
这个应有助于减轻痛楚。