Definition: used as the past form of 'can' to talk about what someone or something was able to do Level: A2
我五岁的时候就能自己系鞋带了。
When I was five, I ___could tie my shoes by myself.
我小时候能跑得很快。
When I was young, I ___could run very fast.
噪音太大了，我们听不清彼此说话。
It was so noisy that we ___could not hear each other.
