I can volunteer you can volunteer he can volunteer we can volunteer you can volunteer they can volunteer
V-ing form
I can be volunteering you can be volunteering he can be volunteering we can be volunteering you can be volunteering they can be volunteering
Perfect
I can have volunteered you can have volunteered he can have volunteered we can have volunteered you can have volunteered they can have volunteered
V-ing perfect
I can have been volunteering you can have been volunteering he can have been volunteering we can have been volunteering you can have been volunteering they can have been volunteering
Negation
Simple form
I can't volunteer you can't volunteer he can't volunteer we can't volunteer you can't volunteer they can't volunteer
V-ing form
I can't be volunteering you can't be volunteering he can't be volunteering we can't be volunteering you can't be volunteering they can't be volunteering
Perfect
I can't have volunteered you can't have volunteered he can't have volunteered we can't have volunteered you can't have volunteered they can't have volunteered
V-ing perfect
I can't have been volunteering you can't have been volunteering he can't have been volunteering we can't have been volunteering you can't have been volunteering they can't have been volunteering
Interrogative form
Simple form
can I volunteer? can you volunteer? can he volunteer? can we volunteer? can you volunteer? can they volunteer?
V-ing form
can I be volunteering? can you be volunteering? can he be volunteering? can we be volunteering? can you be volunteering? can they be volunteering?
Perfect
can I have volunteered? can you have volunteered? can he have volunteered? can we have volunteered? can you have volunteered? can they have volunteered?
V-ing perfect
can I have been volunteering? can you have been volunteering? can he have been volunteering? can we have been volunteering? can you have been volunteering? can they have been volunteering?
Interro-negative form
Simple form
can't I volunteer? can't you volunteer? can't he volunteer? can't we volunteer? can't you volunteer? can't they volunteer?
V-ing form
can't I be volunteering? can't you be volunteering? can't he be volunteering? can't we be volunteering? can't you be volunteering? can't they be volunteering?
Perfect
can't I have volunteered? can't you have volunteered? can't he have volunteered? can't we have volunteered? can't you have volunteered? can't they have volunteered?
V-ing perfect
can't I have been volunteering? can't you have been volunteering? can't he have been volunteering? can't we have been volunteering? can't you have been volunteering? can't they have been volunteering?