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 can't purchase
you can't purchase
she can't purchase
we can't purchase
you can't purchase
they can't purchase 	I can't be purchasing
you can't be purchasing
she can't be purchasing
we can't be purchasing
you can't be purchasing
they can't be purchasing	I can't have purchased
you can't have purchased
she can't have purchased
we can't have purchased
you can't have purchased
they can't have purchased	I can't have been purchasing
you can't have been purchasing
she can't have been purchasing
we can't have been purchasing
you can't have been purchasing
they can't 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't I purchase?
can't you purchase?
can't she purchase?
can't we purchase?
can't you purchase?
can't they purchase? 	can't I be purchasing?
can't you be purchasing?
can't she be purchasing?
can't we be purchasing?
can't you be purchasing?
can't they be purchasing? 	can't I have purchased?
can't you have purchased?
can't she have purchased?
can't we have purchased?
can't you have purchased?
can't they have purchased? 	can't I have been purchasing?
can't you have been purchasing?
can't she have been purchasing?
can't we have been purchasing?
can't you have been purchasing?
can't they have been purchasing?