could bubble
Regular verb: bubble - bubbled- bubbled

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could bubble
you could bubble
he could bubble
we could bubble
you could bubble
they could bubble 	I could be bubbling
you could be bubbling
he could be bubbling
we could be bubbling
you could be bubbling
they could be bubbling	I could have bubbled
you could have bubbled
he could have bubbled
we could have bubbled
you could have bubbled
they could have bubbled	I could have been bubbling
you could have been bubbling
he could have been bubbling
we could have been bubbling
you could have been bubbling
they could have been bubbling	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not bubble
you could not bubble
he could not bubble
we could not bubble
you could not bubble
they could not bubble 	I could not be bubbling
you could not be bubbling
he could not be bubbling
we could not be bubbling
you could not be bubbling
they could not be bubbling	I could not have bubbled
you could not have bubbled
he could not have bubbled
we could not have bubbled
you could not have bubbled
they could not have bubbled	I could not have been bubbling
you could not have been bubbling
he could not have been bubbling
we could not have been bubbling
you could not have been bubbling
they could not have been bubbling	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I bubble?
could you bubble?
could he bubble?
could we bubble?
could you bubble?
could they bubble? 	could I be bubbling?
could you be bubbling?
could he be bubbling?
could we be bubbling?
could you be bubbling?
could they be bubbling? 	could I have bubbled?
could you have bubbled?
could he have bubbled?
could we have bubbled?
could you have bubbled?
could they have bubbled? 	could I have been bubbling?
could you have been bubbling?
could he have been bubbling?
could we have been bubbling?
could you have been bubbling?
could they have been bubbling? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not bubble?
could you not bubble?
could he not bubble?
could we not bubble?
could you not bubble?
could they not bubble? 	could I not be bubbling?
could you not be bubbling?
could he not be bubbling?
could we not be bubbling?
could you not be bubbling?
could they not be bubbling? 	could I not have bubbled?
could you not have bubbled?
could he not have bubbled?
could we not have bubbled?
could you not have bubbled?
could they not have bubbled? 	could I not have been bubbling?
could you not have been bubbling?
could he not have been bubbling?
could we not have been bubbling?
could you not have been bubbling?
could they not have been bubbling?