Davu's detailed explanation of this/that/these/those https://www.duolingo.com/comment/536217
This explanation is very good
Should it accept "You are good in this"?
If I was talking to an actor about a movie?
We' rather say "você está/foi bem nesse filme". Because "bom nisto" is very used as "good at it".
Yes!!... but then I thin one would use "nisso"
What is the difference between "boa" and "bom"?
Boa - female word. Gabi é boa. A mulher é boa. A comida é boa.
Bom - male word. Você (male word) é bom. O homem é bom. Eu sou bom.
What's the difference between "nisso" and "nisto"
nisso = em+isso = in+that (to talk about generic or unknown things)
nisto = em+isto = in+this (to talk about generic or unknown things)