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