endurecimos
-we hardened
The word endurecimos is the preterite form of endurecer in the first person plural.
See the full endurecer conjugation

endurecer

En tanto Parlamento Europeo, endurecimos mucho las normas de emisión en la primera lectura e incluimos, así mismo, las instalaciones de combustión existentes en el ámbito de aplicación de la directiva.
We as Parliament made great improvements to emission standards at first reading, and we also brought existing combustion plants within the scope of the directive.
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