threshold

[ˈθreʃhəʊld]
noun

1.	[doorway] umbral m

2.	[level] límite m the pain threshold el umbral del dolor

3.	(fig) [verge] to be on the threshold of estar en los umbrales or a las puertas de

Parole vicine

threshold

Francese

Tedesco

Italiano

Complétez la séquence avec la proposition qui convient.

America … by Christopher Columbus in 1492.
- discovered
- was discovered
- is discovered