I could fell you could fell he could fell we could fell you could fell they could fell
V-ing form
I could be felling you could be felling he could be felling we could be felling you could be felling they could be felling
Perfect
I could have felled you could have felled he could have felled we could have felled you could have felled they could have felled
V-ing perfect
I could have been felling you could have been felling he could have been felling we could have been felling you could have been felling they could have been felling
Negation
Simple form
I couldn't fell you couldn't fell he couldn't fell we couldn't fell you couldn't fell they couldn't fell
V-ing form
I couldn't be felling you couldn't be felling he couldn't be felling we couldn't be felling you couldn't be felling they couldn't be felling
Perfect
I couldn't have felled you couldn't have felled he couldn't have felled we couldn't have felled you couldn't have felled they couldn't have felled
V-ing perfect
I couldn't have been felling you couldn't have been felling he couldn't have been felling we couldn't have been felling you couldn't have been felling they couldn't have been felling
Interrogative form
Simple form
could I fell? could you fell? could he fell? could we fell? could you fell? could they fell?
V-ing form
could I be felling? could you be felling? could he be felling? could we be felling? could you be felling? could they be felling?
Perfect
could I have felled? could you have felled? could he have felled? could we have felled? could you have felled? could they have felled?
V-ing perfect
could I have been felling? could you have been felling? could he have been felling? could we have been felling? could you have been felling? could they have been felling?
Interro-negative form
Simple form
couldn't I fell? couldn't you fell? couldn't he fell? couldn't we fell? couldn't you fell? couldn't they fell?
V-ing form
couldn't I be felling? couldn't you be felling? couldn't he be felling? couldn't we be felling? couldn't you be felling? couldn't they be felling?
Perfect
couldn't I have felled? couldn't you have felled? couldn't he have felled? couldn't we have felled? couldn't you have felled? couldn't they have felled?
V-ing perfect
couldn't I have been felling? couldn't you have been felling? couldn't he have been felling? couldn't we have been felling? couldn't you have been felling? couldn't they have been felling?