手早い答え
pode は現在、pôde は曲折アクセント付きの完了過去です。
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
pode
can, present
Use pode for the present-tense form of poder.
pôde
could, completed past
Use pôde for the third-person preterite form of poder.
選び方
- pode: Choose pode if the sentence points to the present-tense form of poder.
- pôde: Choose pôde if the sentence points to the third-person preterite form of poder.
例文
Hoje ela pode participar.
Today she can participate.
Ontem ela não pôde participar.
Yesterday she could not participate.
よくある落とし穴
Time words help, but the accent is still required: hoje pode, ontem pôde.
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podeで、もう一度はpôde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。