I can krass you can krass he can krass we can krass you can krass they can krass
V-ing form
I can be krassing you can be krassing he can be krassing we can be krassing you can be krassing they can be krassing
Perfect
I can have krassed you can have krassed he can have krassed we can have krassed you can have krassed they can have krassed
V-ing perfect
I can have been krassing you can have been krassing he can have been krassing we can have been krassing you can have been krassing they can have been krassing
Negation
Simple form
I can't krass you can't krass he can't krass we can't krass you can't krass they can't krass
V-ing form
I can't be krassing you can't be krassing he can't be krassing we can't be krassing you can't be krassing they can't be krassing
Perfect
I can't have krassed you can't have krassed he can't have krassed we can't have krassed you can't have krassed they can't have krassed
V-ing perfect
I can't have been krassing you can't have been krassing he can't have been krassing we can't have been krassing you can't have been krassing they can't have been krassing
Interrogative form
Simple form
can I krass? can you krass? can he krass? can we krass? can you krass? can they krass?
V-ing form
can I be krassing? can you be krassing? can he be krassing? can we be krassing? can you be krassing? can they be krassing?
Perfect
can I have krassed? can you have krassed? can he have krassed? can we have krassed? can you have krassed? can they have krassed?
V-ing perfect
can I have been krassing? can you have been krassing? can he have been krassing? can we have been krassing? can you have been krassing? can they have been krassing?
Interro-negative form
Simple form
can't I krass? can't you krass? can't he krass? can't we krass? can't you krass? can't they krass?
V-ing form
can't I be krassing? can't you be krassing? can't he be krassing? can't we be krassing? can't you be krassing? can't they be krassing?
Perfect
can't I have krassed? can't you have krassed? can't he have krassed? can't we have krassed? can't you have krassed? can't they have krassed?
V-ing perfect
can't I have been krassing? can't you have been krassing? can't he have been krassing? can't we have been krassing? can't you have been krassing? can't they have been krassing?