I can answer you can answer he can answer we can answer you can answer they can answer
V-ing form
I can be answering you can be answering he can be answering we can be answering you can be answering they can be answering
Perfect
I can have answered you can have answered he can have answered we can have answered you can have answered they can have answered
V-ing perfect
I can have been answering you can have been answering he can have been answering we can have been answering you can have been answering they can have been answering
Negation
Simple form
I can't answer you can't answer he can't answer we can't answer you can't answer they can't answer
V-ing form
I can't be answering you can't be answering he can't be answering we can't be answering you can't be answering they can't be answering
Perfect
I can't have answered you can't have answered he can't have answered we can't have answered you can't have answered they can't have answered
V-ing perfect
I can't have been answering you can't have been answering he can't have been answering we can't have been answering you can't have been answering they can't have been answering
Interrogative form
Simple form
can I answer? can you answer? can he answer? can we answer? can you answer? can they answer?
V-ing form
can I be answering? can you be answering? can he be answering? can we be answering? can you be answering? can they be answering?
Perfect
can I have answered? can you have answered? can he have answered? can we have answered? can you have answered? can they have answered?
V-ing perfect
can I have been answering? can you have been answering? can he have been answering? can we have been answering? can you have been answering? can they have been answering?
Interro-negative form
Simple form
can't I answer? can't you answer? can't he answer? can't we answer? can't you answer? can't they answer?
V-ing form
can't I be answering? can't you be answering? can't he be answering? can't we be answering? can't you be answering? can't they be answering?
Perfect
can't I have answered? can't you have answered? can't he have answered? can't we have answered? can't you have answered? can't they have answered?
V-ing perfect
can't I have been answering? can't you have been answering? can't he have been answering? can't we have been answering? can't you have been answering? can't they have been answering?