could callus
Regular verb: callus - callused- callused

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could callus
you could callus
he could callus
we could callus
you could callus
they could callus 	I could be callusing
you could be callusing
he could be callusing
we could be callusing
you could be callusing
they could be callusing	I could have callused
you could have callused
he could have callused
we could have callused
you could have callused
they could have callused	I could have been callusing
you could have been callusing
he could have been callusing
we could have been callusing
you could have been callusing
they could have been callusing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not callus
you could not callus
he could not callus
we could not callus
you could not callus
they could not callus 	I could not be callusing
you could not be callusing
he could not be callusing
we could not be callusing
you could not be callusing
they could not be callusing	I could not have callused
you could not have callused
he could not have callused
we could not have callused
you could not have callused
they could not have callused	I could not have been callusing
you could not have been callusing
he could not have been callusing
we could not have been callusing
you could not have been callusing
they could not have been callusing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I callus?
could you callus?
could he callus?
could we callus?
could you callus?
could they callus? 	could I be callusing?
could you be callusing?
could he be callusing?
could we be callusing?
could you be callusing?
could they be callusing? 	could I have callused?
could you have callused?
could he have callused?
could we have callused?
could you have callused?
could they have callused? 	could I have been callusing?
could you have been callusing?
could he have been callusing?
could we have been callusing?
could you have been callusing?
could they have been callusing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not callus?
could you not callus?
could he not callus?
could we not callus?
could you not callus?
could they not callus? 	could I not be callusing?
could you not be callusing?
could he not be callusing?
could we not be callusing?
could you not be callusing?
could they not be callusing? 	could I not have callused?
could you not have callused?
could he not have callused?
could we not have callused?
could you not have callused?
could they not have callused? 	could I not have been callusing?
could you not have been callusing?
could he not have been callusing?
could we not have been callusing?
could you not have been callusing?
could they not have been callusing?