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