gnaw at

例句：

1. 1. The dog was gnaw atthe bone until it was completely destroyed.
   那只狗一直啃咬骨头，直到它被完全摧毁。
2. 2. Thechild gnawed athis food with a determined lookon his face.
   那个孩子用坚定的眼神啃着他的食物。
3. 3. The tigergnaws at the meat in its mouth, waiting for the right moment to strike.
   老虎在嘴里啃着肉，等待着合适的时机出击。