trowal

例句：

1. 1. The engineers were busy digging a new tunnel to connect the two cities.
   工程师们忙于挖掘一条新的隧道，连接两个城市。
2. 2. The tunnel mouth was covered with snow and ice.
   隧道口被雪和冰覆盖着。
3. 3. The tunnel is so deep that it's hard to see what's on the other side.
   这条隧道非常深，很难看到另一边的情况。