I can descend you can descend he can descend we can descend you can descend they can descend
V-ing form
I can be descending you can be descending he can be descending we can be descending you can be descending they can be descending
Perfect
I can have descended you can have descended he can have descended we can have descended you can have descended they can have descended
V-ing perfect
I can have been descending you can have been descending he can have been descending we can have been descending you can have been descending they can have been descending
Negation
Simple form
I can't descend you can't descend he can't descend we can't descend you can't descend they can't descend
V-ing form
I can't be descending you can't be descending he can't be descending we can't be descending you can't be descending they can't be descending
Perfect
I can't have descended you can't have descended he can't have descended we can't have descended you can't have descended they can't have descended
V-ing perfect
I can't have been descending you can't have been descending he can't have been descending we can't have been descending you can't have been descending they can't have been descending
Interrogative form
Simple form
can I descend? can you descend? can he descend? can we descend? can you descend? can they descend?
V-ing form
can I be descending? can you be descending? can he be descending? can we be descending? can you be descending? can they be descending?
Perfect
can I have descended? can you have descended? can he have descended? can we have descended? can you have descended? can they have descended?
V-ing perfect
can I have been descending? can you have been descending? can he have been descending? can we have been descending? can you have been descending? can they have been descending?
Interro-negative form
Simple form
can't I descend? can't you descend? can't he descend? can't we descend? can't you descend? can't they descend?
V-ing form
can't I be descending? can't you be descending? can't he be descending? can't we be descending? can't you be descending? can't they be descending?
Perfect
can't I have descended? can't you have descended? can't he have descended? can't we have descended? can't you have descended? can't they have descended?
V-ing perfect
can't I have been descending? can't you have been descending? can't he have been descending? can't we have been descending? can't you have been descending? can't they have been descending?