I could learn you could learn he could learn we could learn you could learn they could learn
V-ing form
I could be learning you could be learning he could be learning we could be learning you could be learning they could be learning
Perfect
I could have learned, learnt you could have learned, learnt he could have learned, learnt we could have learned, learnt you could have learned, learnt they could have learned, learnt
V-ing perfect
I could have been learning you could have been learning he could have been learning we could have been learning you could have been learning they could have been learning
Negation
Simple form
I couldn't learn you couldn't learn he couldn't learn we couldn't learn you couldn't learn they couldn't learn
V-ing form
I couldn't be learning you couldn't be learning he couldn't be learning we couldn't be learning you couldn't be learning they couldn't be learning
Perfect
I couldn't have learned, learnt you couldn't have learned, learnt he couldn't have learned, learnt we couldn't have learned, learnt you couldn't have learned, learnt they couldn't have learned, learnt
V-ing perfect
I couldn't have been learning you couldn't have been learning he couldn't have been learning we couldn't have been learning you couldn't have been learning they couldn't have been learning
Interrogative form
Simple form
could I learn? could you learn? could he learn? could we learn? could you learn? could they learn?
V-ing form
could I be learning? could you be learning? could he be learning? could we be learning? could you be learning? could they be learning?
Perfect
could I have learned, learnt? could you have learned, learnt? could he have learned, learnt? could we have learned, learnt? could you have learned, learnt? could they have learned, learnt?
V-ing perfect
could I have been learning? could you have been learning? could he have been learning? could we have been learning? could you have been learning? could they have been learning?
Interro-negative form
Simple form
couldn't I learn? couldn't you learn? couldn't he learn? couldn't we learn? couldn't you learn? couldn't they learn?
V-ing form
couldn't I be learning? couldn't you be learning? couldn't he be learning? couldn't we be learning? couldn't you be learning? couldn't they be learning?
Perfect
couldn't I have learned, learnt? couldn't you have learned, learnt? couldn't he have learned, learnt? couldn't we have learned, learnt? couldn't you have learned, learnt? couldn't they have learned, learnt?
V-ing perfect
couldn't I have been learning? couldn't you have been learning? couldn't he have been learning? couldn't we have been learning? couldn't you have been learning? couldn't they have been learning?