could marble
Regular verb: marble - marbled- marbled

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could marble
you could marble
she could marble
we could marble
you could marble
they could marble 	I could be marbling
you could be marbling
she could be marbling
we could be marbling
you could be marbling
they could be marbling	I could have marbled
you could have marbled
she could have marbled
we could have marbled
you could have marbled
they could have marbled	I could have been marbling
you could have been marbling
she could have been marbling
we could have been marbling
you could have been marbling
they could have been marbling	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not marble
you could not marble
she could not marble
we could not marble
you could not marble
they could not marble 	I could not be marbling
you could not be marbling
she could not be marbling
we could not be marbling
you could not be marbling
they could not be marbling	I could not have marbled
you could not have marbled
she could not have marbled
we could not have marbled
you could not have marbled
they could not have marbled	I could not have been marbling
you could not have been marbling
she could not have been marbling
we could not have been marbling
you could not have been marbling
they could not have been marbling	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I marble?
could you marble?
could she marble?
could we marble?
could you marble?
could they marble? 	could I be marbling?
could you be marbling?
could she be marbling?
could we be marbling?
could you be marbling?
could they be marbling? 	could I have marbled?
could you have marbled?
could she have marbled?
could we have marbled?
could you have marbled?
could they have marbled? 	could I have been marbling?
could you have been marbling?
could she have been marbling?
could we have been marbling?
could you have been marbling?
could they have been marbling? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not marble?
could you not marble?
could she not marble?
could we not marble?
could you not marble?
could they not marble? 	could I not be marbling?
could you not be marbling?
could she not be marbling?
could we not be marbling?
could you not be marbling?
could they not be marbling? 	could I not have marbled?
could you not have marbled?
could she not have marbled?
could we not have marbled?
could you not have marbled?
could they not have marbled? 	could I not have been marbling?
could you not have been marbling?
could she not have been marbling?
could we not have been marbling?
could you not have been marbling?
could they not have been marbling?