In an English text book, I found the following sentence.
a. "The Swiss tunnel took 17 years to build."
(The full article follows.)
"A tunnel" is supposed to be built, so I think
b. The Swiss tunnel took 17 years "to be built".
According to a native speaker, "a." is much better.
Is "build" a verb intransitive in the a.?
In Switzerland, a train has made the first trip using the world’s longest railway tunnel. The tunnel goes through the Alps. It connects Zurich and Lugano.
The train left Zurich on December 11, carrying about 500 passengers. It passed through the 57.1-kilometer-long Gotthard Base Tunnel.
“This is a historic moment,” a male passenger said. “I really wanted to be part of it.”
At the end of the two-hour ride, the train reached Lugano. Passengers were welcomed by crowds and musicians at a train platform.