I can burr you can burr he can burr we can burr you can burr they can burr
V-ing form
I can be burring you can be burring he can be burring we can be burring you can be burring they can be burring
Perfect
I can have burred you can have burred he can have burred we can have burred you can have burred they can have burred
V-ing perfect
I can have been burring you can have been burring he can have been burring we can have been burring you can have been burring they can have been burring
Negation
Simple form
I can't burr you can't burr he can't burr we can't burr you can't burr they can't burr
V-ing form
I can't be burring you can't be burring he can't be burring we can't be burring you can't be burring they can't be burring
Perfect
I can't have burred you can't have burred he can't have burred we can't have burred you can't have burred they can't have burred
V-ing perfect
I can't have been burring you can't have been burring he can't have been burring we can't have been burring you can't have been burring they can't have been burring
Interrogative form
Simple form
can I burr? can you burr? can he burr? can we burr? can you burr? can they burr?
V-ing form
can I be burring? can you be burring? can he be burring? can we be burring? can you be burring? can they be burring?
Perfect
can I have burred? can you have burred? can he have burred? can we have burred? can you have burred? can they have burred?
V-ing perfect
can I have been burring? can you have been burring? can he have been burring? can we have been burring? can you have been burring? can they have been burring?
Interro-negative form
Simple form
can't I burr? can't you burr? can't he burr? can't we burr? can't you burr? can't they burr?
V-ing form
can't I be burring? can't you be burring? can't he be burring? can't we be burring? can't you be burring? can't they be burring?
Perfect
can't I have burred? can't you have burred? can't he have burred? can't we have burred? can't you have burred? can't they have burred?
V-ing perfect
can't I have been burring? can't you have been burring? can't he have been burring? can't we have been burring? can't you have been burring? can't they have been burring?