It's done to protect them from unpleasant or toxic odors.

这样做是为了防止他们受到难闻或有毒气味的影响。

The verb " to smell" in this case means to have a certain odor – an unpleasant smell, an unpleasant odor.

在这种情况下，动词“闻到”的意思是有某种气味——一种难闻的气味，一种难闻的气味。

The verb " to stink" is an informal way of saying that someone smells bad, they have an unpleasant smell or an unpleasant odor.

动词“发臭” 是一种非正式的说法， 表示某人闻起来很臭， 他们有难闻的气味或难闻的气味。

They had passed but a short distance to the rear of Numa when the boy caught the unpleasant odor of the carnivore. His face lighted with a smile.

当男孩闻到食肉动物难闻的气味时，他们刚从努马的后方走过不远。他的脸上露出了笑容。