Past Tense (to be)

In Ecuador, the first oil well ___ discovered in Ancon, Santa Elena peninsula.

Anglo declared in 1967 that the Santa Elena fields ___ almost exhausted.

Oil exploitation ___ concentrated in the Santa Elena peninsula.

The decline of the first wells ___ such that the country stopped exporting crude oil between 1960 and 1971.

The only oil produced ___ for self-consumption, according to Byron Galarza's book "El Petróleo en el Ecuador".

It ___ in the 1960s when the governments of the time granted concessions for another 5 million hectares in northeastern Ecuador.

Each barrel ___ sold at US$2.34.