I could krass you could krass she could krass we could krass you could krass they could krass
V-ing form
I could be krassing you could be krassing she could be krassing we could be krassing you could be krassing they could be krassing
Perfect
I could have krassed you could have krassed she 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 she could have been krassing we could have been krassing you could have been krassing they could have been krassing
Negation
Simple form
I could not krass you could not krass she could not krass we could not krass you could not krass they could not krass
V-ing form
I could not be krassing you could not be krassing she could not be krassing we could not be krassing you could not be krassing they could not be krassing
Perfect
I could not have krassed you could not have krassed she could not have krassed we could not have krassed you could not have krassed they could not have krassed
V-ing perfect
I could not have been krassing you could not have been krassing she could not have been krassing we could not have been krassing you could not have been krassing they could not have been krassing
Interrogative form
Simple form
could I krass? could you krass? could she krass? could we krass? could you krass? could they krass?
V-ing form
could I be krassing? could you be krassing? could she be krassing? could we be krassing? could you be krassing? could they be krassing?
Perfect
could I have krassed? could you have krassed? could she 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 she have been krassing? could we have been krassing? could you have been krassing? could they have been krassing?
Interro-negative form
Simple form
could I not krass? could you not krass? could she not krass? could we not krass? could you not krass? could they not krass?
V-ing form
could I not be krassing? could you not be krassing? could she not be krassing? could we not be krassing? could you not be krassing? could they not be krassing?
Perfect
could I not have krassed? could you not have krassed? could she not have krassed? could we not have krassed? could you not have krassed? could they not have krassed?
V-ing perfect
could I not have been krassing? could you not have been krassing? could she not have been krassing? could we not have been krassing? could you not have been krassing? could they not have been krassing?