English verb conjugation
CAN PURCHASE

Regular verb: purchase - purchased - purchased

Affirmation

Simple form	V-ing form
I can purchase you can purchase he can purchase we can purchase you can purchase they can purchase	I can be purchasing you can be purchasing he can be purchasing we can be purchasing you can be purchasing they can be purchasing
Perfect	V-ing perfect
I can have purchased you can have purchased he 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 he 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
I can't purchase you can't purchase he 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 he can't be purchasing we can't be purchasing you can't be purchasing they can't be purchasing
Perfect	V-ing perfect
I can't have purchased you can't have purchased he 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 he 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
can I purchase? can you purchase? can he purchase? can we purchase? can you purchase? can they purchase?	can I be purchasing? can you be purchasing? can he be purchasing? can we be purchasing? can you be purchasing? can they be purchasing?
Perfect	V-ing perfect
can I have purchased? can you have purchased? can he 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 he 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
can't I purchase? can't you purchase? can't he 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 he be purchasing? can't we be purchasing? can't you be purchasing? can't they be purchasing?
Perfect	V-ing perfect
can't I have purchased? can't you have purchased? can't he 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 he have been purchasing? can't we have been purchasing? can't you have been purchasing? can't they have been purchasing?