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 couldn't callus
you couldn't callus
he couldn't callus
we couldn't callus
you couldn't callus
they couldn't callus 	I couldn't be callusing
you couldn't be callusing
he couldn't be callusing
we couldn't be callusing
you couldn't be callusing
they couldn't be callusing	I couldn't have callused
you couldn't have callused
he couldn't have callused
we couldn't have callused
you couldn't have callused
they couldn't have callused	I couldn't have been callusing
you couldn't have been callusing
he couldn't have been callusing
we couldn't have been callusing
you couldn't have been callusing
they couldn't 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 	
couldn't I callus?
couldn't you callus?
couldn't he callus?
couldn't we callus?
couldn't you callus?
couldn't they callus? 	couldn't I be callusing?
couldn't you be callusing?
couldn't he be callusing?
couldn't we be callusing?
couldn't you be callusing?
couldn't they be callusing? 	couldn't I have callused?
couldn't you have callused?
couldn't he have callused?
couldn't we have callused?
couldn't you have callused?
couldn't they have callused? 	couldn't I have been callusing?
couldn't you have been callusing?
couldn't he have been callusing?
couldn't we have been callusing?
couldn't you have been callusing?
couldn't they have been callusing?