Or bugs, which leave these red or blue stains.

或者是虫子，会留红色或蓝色污渍。

He wiped away the blue stain above his lip with the back of his arm, then let out the tiniest burp.

他用胳膊背擦去嘴唇上方蓝色污渍， 然后打了个最小嗝。

Here's a classic histology image of cirrhotic tissue, this clump of cells in the middle is the regenerative nodule, and these blue stains surrounding it are the bands of protein from the process of fibrosis.

是张典型肝硬化组织组织学图像，中间圈分堆细胞就是再生结节，包围再生结节蓝色区域是肝脏纤维化过程中形成蛋白质束。