工人们正在修建一条穿过山体的隧道。

Workers are building a ___tunnel through the mountain.

我们穿过了一条鲜花覆盖的隧道。

We walked through a flower-covered ___tunnel.

工程师们正在山底下挖掘隧道以修建新的铁路。

Engineers are ___tunneling under the mountain to build a new railway.