I can defend you can defend he can defend we can defend you can defend they can defend
V-ing form
I can be defending you can be defending he can be defending we can be defending you can be defending they can be defending
Perfect
I can have defended you can have defended he can have defended we can have defended you can have defended they can have defended
V-ing perfect
I can have been defending you can have been defending he can have been defending we can have been defending you can have been defending they can have been defending
Negation
Simple form
I can't defend you can't defend he can't defend we can't defend you can't defend they can't defend
V-ing form
I can't be defending you can't be defending he can't be defending we can't be defending you can't be defending they can't be defending
Perfect
I can't have defended you can't have defended he can't have defended we can't have defended you can't have defended they can't have defended
V-ing perfect
I can't have been defending you can't have been defending he can't have been defending we can't have been defending you can't have been defending they can't have been defending
Interrogative form
Simple form
can I defend? can you defend? can he defend? can we defend? can you defend? can they defend?
V-ing form
can I be defending? can you be defending? can he be defending? can we be defending? can you be defending? can they be defending?
Perfect
can I have defended? can you have defended? can he have defended? can we have defended? can you have defended? can they have defended?
V-ing perfect
can I have been defending? can you have been defending? can he have been defending? can we have been defending? can you have been defending? can they have been defending?
Interro-negative form
Simple form
can't I defend? can't you defend? can't he defend? can't we defend? can't you defend? can't they defend?
V-ing form
can't I be defending? can't you be defending? can't he be defending? can't we be defending? can't you be defending? can't they be defending?
Perfect
can't I have defended? can't you have defended? can't he have defended? can't we have defended? can't you have defended? can't they have defended?
V-ing perfect
can't I have been defending? can't you have been defending? can't he have been defending? can't we have been defending? can't you have been defending? can't they have been defending?