could vs, was/were able to

・「~できる」と言う場合、”can”か”be able to”で表す。

[正]I can swim.
[正]I am able to swim.

・「能力があった」という意味で「~できた」と言う場合、”could”か”be able to”で表す。

[正]I could play the piano when I was 4 years old.
[正]I was able to play the piano when I was 4 years old.

・「実際にした」という意味で「~できた」と言う場合、”be able to”か過去形で表す。
・日本人は、”I don’t understand”と言うべきところを”I can’t understand”と言ったり、単に過去形で言うところを、「~できた」と表現する傾向があるので注意が必要である。

[誤]Because I talked to my husband nicely, I could convince him.
[正]Because I talked to my husband mother nicely, I was able to convince him.
[正]Because I talked to my husband nicely, I convinced him.

[誤]I could study math last Sunday.
[正]I was able to study math last Sunday.
[正]I studied math last Sunday.

could vs, was/were able toの関連項目