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 could not krass you could not krass he 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 he 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 he 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 he 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 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
could I not krass? could you not krass? could he 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 he 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 he 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 he not have been krassing? could we not have been krassing? could you not have been krassing? could they not have been krassing?