I can contend you can contend he can contend we can contend you can contend they can contend
V-ing form
I can be contending you can be contending he can be contending we can be contending you can be contending they can be contending
Perfect
I can have contended you can have contended he can have contended we can have contended you can have contended they can have contended
V-ing perfect
I can have been contending you can have been contending he can have been contending we can have been contending you can have been contending they can have been contending
Negation
Simple form
I cannot contend you cannot contend he cannot contend we cannot contend you cannot contend they cannot contend
V-ing form
I cannot be contending you cannot be contending he cannot be contending we cannot be contending you cannot be contending they cannot be contending
Perfect
I cannot have contended you cannot have contended he cannot have contended we cannot have contended you cannot have contended they cannot have contended
V-ing perfect
I cannot have been contending you cannot have been contending he cannot have been contending we cannot have been contending you cannot have been contending they cannot have been contending
Interrogative form
Simple form
can I contend? can you contend? can he contend? can we contend? can you contend? can they contend?
V-ing form
can I be contending? can you be contending? can he be contending? can we be contending? can you be contending? can they be contending?
Perfect
can I have contended? can you have contended? can he have contended? can we have contended? can you have contended? can they have contended?
V-ing perfect
can I have been contending? can you have been contending? can he have been contending? can we have been contending? can you have been contending? can they have been contending?
Interro-negative form
Simple form
can I not contend? can you not contend? can he not contend? can we not contend? can you not contend? can they not contend?
V-ing form
can I not be contending? can you not be contending? can he not be contending? can we not be contending? can you not be contending? can they not be contending?
Perfect
can I not have contended? can you not have contended? can he not have contended? can we not have contended? can you not have contended? can they not have contended?
V-ing perfect
can I not have been contending? can you not have been contending? can he not have been contending? can we not have been contending? can you not have been contending? can they not have been contending?