vaginal fluid stain

例句：

1. 1.The doctor used a special stain to identify the cause of the infection.
   医生使用一种特殊的染色剂来识别感染的原因。
2. 2. The stain on the fabric was caused by the acid in the urine.
   布料上的污渍是由尿液中的酸引起的。
3. 3. The stain on the wall was due to the spilled food.
   墙上的污渍是由于溢出的食物引起的。