Emphasizing who and where (foi quem, é onde)

Highlighting "Who"

When you want to place special emphasis on exactly who did something—like pinpointing who made a groundbreaking scientific discovery—Portuguese uses a cleft sentence. To express "It was [person] who...", use foi (the past tense of ser, meaning "it was") followed by the person, and then quem (who).

It was the inventor who discovered the radiation.
Foi o inventor quem descobriu a radiação.
It was the researcher who wrote the equation.
Foi o investigador quem escreveu a equação.

Highlighting "Where"

To emphasize the specific location where the magic happens, use a form of the verb ser (such as é for "it is") followed by the place, and then onde (where).

It is in the laboratory where the physicist works.
É no laboratório onde o físico trabalha.
It is in the university where they measure radiation.
É na universidade onde medem a radiação.

Highlighting "When"

Similarly, when you need to stress the exact moment or timeframe of an event, use a form of ser plus the time phrase, followed by quando (when).

It was yesterday when he understood gravity.
Foi ontem quando ele compreendeu a gravidade.
It was in autumn when they made penicillin.
Foi no outono quando fizeram a penicilina.