Vampire bats have very strong teeth that are sharp enough to bite through the skin of animals.
这个是网上的一些讨论，希望对你有帮助：https://ell.stackexchange.com/q/79074/172656
use into for a substance that will be absorbed by the skin; on or onto for a substance that will remain on the surface. You'll need the appropriate verb in each instance. Spread means cover a surface, so it's inapt with into.
被蚊子叮了，你的substance 一定有变化，所以用 into。
我认为是写 into/inside（意思是：（咬）入）
Why? Reason:因为动物它们都是用 尖牙 咬入动物的身体里面，才能动物杀死。 谢谢
