can purchase
Regular verb: purchase - purchased- purchased

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I can purchase
you can purchase
she can purchase
we can purchase
you can purchase
they can purchase 	I can be purchasing
you can be purchasing
she can be purchasing
we can be purchasing
you can be purchasing
they can be purchasing	I can have purchased
you can have purchased
she can have purchased
we can have purchased
you can have purchased
they can have purchased	I can have been purchasing
you can have been purchasing
she can have been purchasing
we can have been purchasing
you can have been purchasing
they can have been purchasing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I cannot purchase
you cannot purchase
she cannot purchase
we cannot purchase
you cannot purchase
they cannot purchase 	I cannot be purchasing
you cannot be purchasing
she cannot be purchasing
we cannot be purchasing
you cannot be purchasing
they cannot be purchasing	I cannot have purchased
you cannot have purchased
she cannot have purchased
we cannot have purchased
you cannot have purchased
they cannot have purchased	I cannot have been purchasing
you cannot have been purchasing
she cannot have been purchasing
we cannot have been purchasing
you cannot have been purchasing
they cannot have been purchasing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can I purchase?
can you purchase?
can she purchase?
can we purchase?
can you purchase?
can they purchase? 	can I be purchasing?
can you be purchasing?
can she be purchasing?
can we be purchasing?
can you be purchasing?
can they be purchasing? 	can I have purchased?
can you have purchased?
can she have purchased?
can we have purchased?
can you have purchased?
can they have purchased? 	can I have been purchasing?
can you have been purchasing?
can she have been purchasing?
can we have been purchasing?
can you have been purchasing?
can they have been purchasing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
can I not purchase?
can you not purchase?
can she not purchase?
can we not purchase?
can you not purchase?
can they not purchase? 	can I not be purchasing?
can you not be purchasing?
can she not be purchasing?
can we not be purchasing?
can you not be purchasing?
can they not be purchasing? 	can I not have purchased?
can you not have purchased?
can she not have purchased?
can we not have purchased?
can you not have purchased?
can they not have purchased? 	can I not have been purchasing?
can you not have been purchasing?
can she not have been purchasing?
can we not have been purchasing?
can you not have been purchasing?
can they not have been purchasing?