❶～することができた ⦣ can （できる）の過去形.
No one could answer this question.
No one could answer this question.
誰だれもこの問いに答えられなかった.
Bob ran as fast as he could.
Bob ran as fast as he could.
ボブはできるだけ速く走った.
✓POINT
主節の動詞 （ran＝runの過去）と同じ過去の「時」を示すために can の過去である could を用いたもの. 訳す時は主節の動詞のほうだけを過去（走った）にすればよい. 次の例も同じ.
John said (that) he could swim across the river.=John said, "I can swim across the river."
John said (that) he could swim across the river.=John said, “I can swim across the river.”
ジョンはその川を泳いで渡わたれると言った.
I wish I could speak English well.
I wish I could speak English well.
（今は話せないが）英語を上手に話せたらなあ.
⦣ 仮定法, 現在の事実とは異なることをいう.
