If you areable todo something, you have the necessary physical strength, mental power, skill, time, money, or opportunity to do it.
I wasn't able to work out what she was trying to say.
Canhas a similar meaning and is more common thanable toin speech and writing.
Can you make out what she is trying to say?
The opposite of andableisunable.
I was unable to get the lid off the jar.
You can say that a person or groupis capable ofsomething oris capable of doingsomething.
You are capable of a lot more than you think you are.
I didn't think he was capable of doing that.
The opposite ofbeing capable of (doing)something isbeing incapable of (doing)something.
He was incapable of putting a coherent sentence together.
If youknow how todo something, you have learned how to do it.
"Do you know how to swim?" "Of course I know how to swim."