I can skitter you can skitter he can skitter we can skitter you can skitter they can skitter
V-ing form
I can be skittering you can be skittering he can be skittering we can be skittering you can be skittering they can be skittering
Perfect
I can have skittered you can have skittered he can have skittered we can have skittered you can have skittered they can have skittered
V-ing perfect
I can have been skittering you can have been skittering he can have been skittering we can have been skittering you can have been skittering they can have been skittering
Negation
Simple form
I cannot skitter you cannot skitter he cannot skitter we cannot skitter you cannot skitter they cannot skitter
V-ing form
I cannot be skittering you cannot be skittering he cannot be skittering we cannot be skittering you cannot be skittering they cannot be skittering
Perfect
I cannot have skittered you cannot have skittered he cannot have skittered we cannot have skittered you cannot have skittered they cannot have skittered
V-ing perfect
I cannot have been skittering you cannot have been skittering he cannot have been skittering we cannot have been skittering you cannot have been skittering they cannot have been skittering
Interrogative form
Simple form
can I skitter? can you skitter? can he skitter? can we skitter? can you skitter? can they skitter?
V-ing form
can I be skittering? can you be skittering? can he be skittering? can we be skittering? can you be skittering? can they be skittering?
Perfect
can I have skittered? can you have skittered? can he have skittered? can we have skittered? can you have skittered? can they have skittered?
V-ing perfect
can I have been skittering? can you have been skittering? can he have been skittering? can we have been skittering? can you have been skittering? can they have been skittering?
Interro-negative form
Simple form
can I not skitter? can you not skitter? can he not skitter? can we not skitter? can you not skitter? can they not skitter?
V-ing form
can I not be skittering? can you not be skittering? can he not be skittering? can we not be skittering? can you not be skittering? can they not be skittering?
Perfect
can I not have skittered? can you not have skittered? can he not have skittered? can we not have skittered? can you not have skittered? can they not have skittered?
V-ing perfect
can I not have been skittering? can you not have been skittering? can he not have been skittering? can we not have been skittering? can you not have been skittering? can they not have been skittering?