English verb conjugation
CAN CONCUSS

Regular verb: concuss - concussed - concussed

Affirmation

Simple form	V-ing form
I can concuss you can concuss he can concuss we can concuss you can concuss they can concuss	I can be concussing you can be concussing he can be concussing we can be concussing you can be concussing they can be concussing
Perfect	V-ing perfect
I can have concussed you can have concussed he can have concussed we can have concussed you can have concussed they can have concussed	I can have been concussing you can have been concussing he can have been concussing we can have been concussing you can have been concussing they can have been concussing

Negation

Simple form	V-ing form
I can't concuss you can't concuss he can't concuss we can't concuss you can't concuss they can't concuss	I can't be concussing you can't be concussing he can't be concussing we can't be concussing you can't be concussing they can't be concussing
Perfect	V-ing perfect
I can't have concussed you can't have concussed he can't have concussed we can't have concussed you can't have concussed they can't have concussed	I can't have been concussing you can't have been concussing he can't have been concussing we can't have been concussing you can't have been concussing they can't have been concussing

Interrogative form

Simple form	V-ing form
can I concuss? can you concuss? can he concuss? can we concuss? can you concuss? can they concuss?	can I be concussing? can you be concussing? can he be concussing? can we be concussing? can you be concussing? can they be concussing?
Perfect	V-ing perfect
can I have concussed? can you have concussed? can he have concussed? can we have concussed? can you have concussed? can they have concussed?	can I have been concussing? can you have been concussing? can he have been concussing? can we have been concussing? can you have been concussing? can they have been concussing?

Interro-negative form

Simple form	V-ing form
can't I concuss? can't you concuss? can't he concuss? can't we concuss? can't you concuss? can't they concuss?	can't I be concussing? can't you be concussing? can't he be concussing? can't we be concussing? can't you be concussing? can't they be concussing?
Perfect	V-ing perfect
can't I have concussed? can't you have concussed? can't he have concussed? can't we have concussed? can't you have concussed? can't they have concussed?	can't I have been concussing? can't you have been concussing? can't he have been concussing? can't we have been concussing? can't you have been concussing? can't they have been concussing?