I can flutter you can flutter he can flutter we can flutter you can flutter they can flutter
V-ing form
I can be fluttering you can be fluttering he can be fluttering we can be fluttering you can be fluttering they can be fluttering
Perfect
I can have fluttered you can have fluttered he can have fluttered we can have fluttered you can have fluttered they can have fluttered
V-ing perfect
I can have been fluttering you can have been fluttering he can have been fluttering we can have been fluttering you can have been fluttering they can have been fluttering
Negation
Simple form
I can't flutter you can't flutter he can't flutter we can't flutter you can't flutter they can't flutter
V-ing form
I can't be fluttering you can't be fluttering he can't be fluttering we can't be fluttering you can't be fluttering they can't be fluttering
Perfect
I can't have fluttered you can't have fluttered he can't have fluttered we can't have fluttered you can't have fluttered they can't have fluttered
V-ing perfect
I can't have been fluttering you can't have been fluttering he can't have been fluttering we can't have been fluttering you can't have been fluttering they can't have been fluttering
Interrogative form
Simple form
can I flutter? can you flutter? can he flutter? can we flutter? can you flutter? can they flutter?
V-ing form
can I be fluttering? can you be fluttering? can he be fluttering? can we be fluttering? can you be fluttering? can they be fluttering?
Perfect
can I have fluttered? can you have fluttered? can he have fluttered? can we have fluttered? can you have fluttered? can they have fluttered?
V-ing perfect
can I have been fluttering? can you have been fluttering? can he have been fluttering? can we have been fluttering? can you have been fluttering? can they have been fluttering?
Interro-negative form
Simple form
can't I flutter? can't you flutter? can't he flutter? can't we flutter? can't you flutter? can't they flutter?
V-ing form
can't I be fluttering? can't you be fluttering? can't he be fluttering? can't we be fluttering? can't you be fluttering? can't they be fluttering?
Perfect
can't I have fluttered? can't you have fluttered? can't he have fluttered? can't we have fluttered? can't you have fluttered? can't they have fluttered?
V-ing perfect
can't I have been fluttering? can't you have been fluttering? can't he have been fluttering? can't we have been fluttering? can't you have been fluttering? can't they have been fluttering?