English verb conjugation
CAN CONTRIBUTE

Regular verb: contribute - contributed - contributed

Affirmation

Simple form	V-ing form
I can contribute you can contribute she can contribute we can contribute you can contribute they can contribute	I can be contributing you can be contributing she can be contributing we can be contributing you can be contributing they can be contributing
Perfect	V-ing perfect
I can have contributed you can have contributed she can have contributed we can have contributed you can have contributed they can have contributed	I can have been contributing you can have been contributing she can have been contributing we can have been contributing you can have been contributing they can have been contributing

Negation

Simple form	V-ing form
I can't contribute you can't contribute she can't contribute we can't contribute you can't contribute they can't contribute	I can't be contributing you can't be contributing she can't be contributing we can't be contributing you can't be contributing they can't be contributing
Perfect	V-ing perfect
I can't have contributed you can't have contributed she can't have contributed we can't have contributed you can't have contributed they can't have contributed	I can't have been contributing you can't have been contributing she can't have been contributing we can't have been contributing you can't have been contributing they can't have been contributing

Interrogative form

Simple form	V-ing form
can I contribute? can you contribute? can she contribute? can we contribute? can you contribute? can they contribute?	can I be contributing? can you be contributing? can she be contributing? can we be contributing? can you be contributing? can they be contributing?
Perfect	V-ing perfect
can I have contributed? can you have contributed? can she have contributed? can we have contributed? can you have contributed? can they have contributed?	can I have been contributing? can you have been contributing? can she have been contributing? can we have been contributing? can you have been contributing? can they have been contributing?

Interro-negative form

Simple form	V-ing form
can't I contribute? can't you contribute? can't she contribute? can't we contribute? can't you contribute? can't they contribute?	can't I be contributing? can't you be contributing? can't she be contributing? can't we be contributing? can't you be contributing? can't they be contributing?
Perfect	V-ing perfect
can't I have contributed? can't you have contributed? can't she have contributed? can't we have contributed? can't you have contributed? can't they have contributed?	can't I have been contributing? can't you have been contributing? can't she have been contributing? can't we have been contributing? can't you have been contributing? can't they have been contributing?