Tiny open sores, or ulcers, form on the surface of the lining, where they bleed and produce pus and mucus.

内层表面形成小的开放性疮口(溃疡)，会发生出血并产生脓液和粘液。

youdao

Tiny open sores, or ulcers, form on the surface of the lining, where they bleed and produce pus and mucus.

内层表面形成小的开放性疮口(溃疡)，会发生出血并产生脓液和粘液。

youdao