could clog
Regular verb: clog - clogged- clogged

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could clog
you could clog
he could clog
we could clog
you could clog
they could clog 	I could be clogging
you could be clogging
he could be clogging
we could be clogging
you could be clogging
they could be clogging	I could have clogged
you could have clogged
he could have clogged
we could have clogged
you could have clogged
they could have clogged	I could have been clogging
you could have been clogging
he could have been clogging
we could have been clogging
you could have been clogging
they could have been clogging	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not clog
you could not clog
he could not clog
we could not clog
you could not clog
they could not clog 	I could not be clogging
you could not be clogging
he could not be clogging
we could not be clogging
you could not be clogging
they could not be clogging	I could not have clogged
you could not have clogged
he could not have clogged
we could not have clogged
you could not have clogged
they could not have clogged	I could not have been clogging
you could not have been clogging
he could not have been clogging
we could not have been clogging
you could not have been clogging
they could not have been clogging	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I clog?
could you clog?
could he clog?
could we clog?
could you clog?
could they clog? 	could I be clogging?
could you be clogging?
could he be clogging?
could we be clogging?
could you be clogging?
could they be clogging? 	could I have clogged?
could you have clogged?
could he have clogged?
could we have clogged?
could you have clogged?
could they have clogged? 	could I have been clogging?
could you have been clogging?
could he have been clogging?
could we have been clogging?
could you have been clogging?
could they have been clogging? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not clog?
could you not clog?
could he not clog?
could we not clog?
could you not clog?
could they not clog? 	could I not be clogging?
could you not be clogging?
could he not be clogging?
could we not be clogging?
could you not be clogging?
could they not be clogging? 	could I not have clogged?
could you not have clogged?
could he not have clogged?
could we not have clogged?
could you not have clogged?
could they not have clogged? 	could I not have been clogging?
could you not have been clogging?
could he not have been clogging?
could we not have been clogging?
could you not have been clogging?
could they not have been clogging?