手早い答え
chão は足元の面、piso は施工された床材や仕上げを強調しがちです。
確実な見分け方は、英語から訳す前に、その単語の働きを見きわめることです。
それぞれの単語の働き
chão
ground or floor
Use chão for the surface people stand on, indoors or outdoors.
piso
flooring or paved surface
Use piso for the built material or finish covering a floor.
選び方
- chão: Choose chão if the sentence points to the surface people stand on, indoors or outdoors.
- piso: Choose piso if the sentence points to the built material or finish covering a floor.
例文
O copo caiu no chão.
The glass fell on the floor.
Vamos trocar o piso do banheiro.
We are going to replace the bathroom flooring.
よくある落とし穴
They overlap indoors, but trocar o chão sounds broader than trocar o piso, which clearly points to the floor covering.
文脈の中で練習する
自分の実生活から文を一つ選び、二回書いてみましょう。一度はchãoで、もう一度はpisoで。どちらも成り立ちそうなら、意味の違いを言葉にしてみましょう。