Warning, this verb may not exist. Conjugation is given as example.
Affirmation
Simple form
I could buy buy you could buy buy he could buy buy we could buy buy you could buy buy they could buy buy
V-ing form
I could be buy buying you could be buy buying he could be buy buying we could be buy buying you could be buy buying they could be buy buying
Perfect
I could have buy buyed you could have buy buyed he could have buy buyed we could have buy buyed you could have buy buyed they could have buy buyed
V-ing perfect
I could have been buy buying you could have been buy buying he could have been buy buying we could have been buy buying you could have been buy buying they could have been buy buying
Negation
Simple form
I could not buy buy you could not buy buy he could not buy buy we could not buy buy you could not buy buy they could not buy buy
V-ing form
I could not be buy buying you could not be buy buying he could not be buy buying we could not be buy buying you could not be buy buying they could not be buy buying
Perfect
I could not have buy buyed you could not have buy buyed he could not have buy buyed we could not have buy buyed you could not have buy buyed they could not have buy buyed
V-ing perfect
I could not have been buy buying you could not have been buy buying he could not have been buy buying we could not have been buy buying you could not have been buy buying they could not have been buy buying
Interrogative form
Simple form
could I buy buy? could you buy buy? could he buy buy? could we buy buy? could you buy buy? could they buy buy?
V-ing form
could I be buy buying? could you be buy buying? could he be buy buying? could we be buy buying? could you be buy buying? could they be buy buying?
Perfect
could I have buy buyed? could you have buy buyed? could he have buy buyed? could we have buy buyed? could you have buy buyed? could they have buy buyed?
V-ing perfect
could I have been buy buying? could you have been buy buying? could he have been buy buying? could we have been buy buying? could you have been buy buying? could they have been buy buying?
Interro-negative form
Simple form
could I not buy buy? could you not buy buy? could he not buy buy? could we not buy buy? could you not buy buy? could they not buy buy?
V-ing form
could I not be buy buying? could you not be buy buying? could he not be buy buying? could we not be buy buying? could you not be buy buying? could they not be buy buying?
Perfect
could I not have buy buyed? could you not have buy buyed? could he not have buy buyed? could we not have buy buyed? could you not have buy buyed? could they not have buy buyed?
V-ing perfect
could I not have been buy buying? could you not have been buy buying? could he not have been buy buying? could we not have been buy buying? could you not have been buy buying? could they not have been buy buying?