could
01
可以, 能
used as the past tense of ‘can’
例子
Yesterday, I could see the stars clearly in the night sky.
昨天，我可以清晰地看到夜空中的星星。
02
你可以, 你能
used to ask if one can do something
Transitive
例子
Could you help me with my homework?
你能帮我做作业吗？
03
可能, 可以
used to show the possibility of something happening or being the case
Transitive
04
可以, 能
used to present an offer or recommendation
Transitive
