鼹鼠是一种出色的挖洞者，能在花园里挖出复杂的隧道系统。

The mole is an excellent ___burrower, capable of digging complex tunnel systems in gardens.

兔子在地下挖洞筑巢。

The rabbit ___burrows underground to make its nest.

他在图书馆的档案室里仔细查阅资料，寻找有关这个历史事件的线索。

He ___burrowed through the library archives, searching for clues about the historical event.