it's because it's another verb: Ficar.
"ficar" doesn't have a direct translation to english. depending on the context, it can mean:
* "to stay" (eu fiquei em casa);
* "to be" (a cópia ficou boa?). note that there is a small difference between saying "a cópia ESTÁ boa" and "a cópia FICOU boa". in the second one, it's more like you're saying "the copy ended up well";
* in popular language (at least in brazil), "ficar" can also mean "to date/to make out" (eles ficaram na festa).