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