手早い答え
mas は対比、mais は増加や追加を表します。
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
mas
but
Use mas for contrasting one statement with another.
mais
more or plus
Use mais for a larger amount, addition, or comparison.
選び方
- mas: Choose mas if the sentence points to contrasting one statement with another.
- mais: Choose mais if the sentence points to a larger amount, addition, or comparison.
例文
Quero ir, mas estou cansado.
I want to go, but I am tired.
Quero mais café.
I want more coffee.
よくある落とし穴
They sound very similar in much of Brazil. Replace mas with porém or mais with menos to test the meaning.
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masで、もう一度はmais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。