could do it
Я мог это сделать и без твоей помощи.
I could have done it without your help.
Том не мог это сделать.
Tom couldn't have done it.
Who could have done this?
Я думаю, Том мог это сделать.
I think Tom could have done it.
Том мог это сделать?
Could Tom do this?
Any one of us could have done it.
Если бы Том мог это сделать, он бы уже это сделал.
If Tom could do it, he would have done it already.
Теоретически Том мог это сделать.
Theoretically, Tom could have done it.
You could have done it.