could的同义短语

could的同义短语？

同义词短语: was/were able to

I am able to express my idea in a clear way.

我能清楚地表达自己的想法。

I could / was able to play the piano when I was young.

我年轻时会弹钢琴。

Though he was sick, he was able to swim across the river.

虽然他病了，但他还是游过了河。

After five hours of climbing, we were able to reach the top of the mountain.

经过5个小时的攀爬，我们终于登上了山顶。

I was able to pass the examination. 我通过了考试。

I could pass the examination.

我当时有能力通过考试。