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