Red squirrels disappear inside trees, frogs go deep under the mud, and many other animals dig tunnels in the earth.
红松鼠藏到树里面去了；青蛙钻入泥土的深处。而许多其它的动物，则在地里挖坑道。
A tunnel dug to intercept and destroy an enemy's mine.
对抗地道截断或破坏敌人坑道而挖的地道
The tunnel contract to a narrow passageway as you go deep.
再往里走，坑道缩小成了一条窄窄的通道。
