gnaw

The dog was gnawing a bone.那只狗正在啃骨头。

He nervously gnawed on his fingernails.他紧张地啃着自己的指甲。

Rabbits have gnawed at the hedge.兔子把树篱啃了。

Rabbits had gnawed a hole in the hedge.兔子把树篱啃出个洞。

Squirrels had gnawed their way into the attic. [=they had entered the attic by chewing a hole]松鼠把阁楼咬出个洞，钻了进去。