could penetrate
Regular verb: penetrate - penetrated- penetrated

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could penetrate
you could penetrate
she could penetrate
we could penetrate
you could penetrate
they could penetrate 	I could be penetrating
you could be penetrating
she could be penetrating
we could be penetrating
you could be penetrating
they could be penetrating	I could have penetrated
you could have penetrated
she could have penetrated
we could have penetrated
you could have penetrated
they could have penetrated	I could have been penetrating
you could have been penetrating
she could have been penetrating
we could have been penetrating
you could have been penetrating
they could have been penetrating	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't penetrate
you couldn't penetrate
she couldn't penetrate
we couldn't penetrate
you couldn't penetrate
they couldn't penetrate 	I couldn't be penetrating
you couldn't be penetrating
she couldn't be penetrating
we couldn't be penetrating
you couldn't be penetrating
they couldn't be penetrating	I couldn't have penetrated
you couldn't have penetrated
she couldn't have penetrated
we couldn't have penetrated
you couldn't have penetrated
they couldn't have penetrated	I couldn't have been penetrating
you couldn't have been penetrating
she couldn't have been penetrating
we couldn't have been penetrating
you couldn't have been penetrating
they couldn't have been penetrating	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I penetrate?
could you penetrate?
could she penetrate?
could we penetrate?
could you penetrate?
could they penetrate? 	could I be penetrating?
could you be penetrating?
could she be penetrating?
could we be penetrating?
could you be penetrating?
could they be penetrating? 	could I have penetrated?
could you have penetrated?
could she have penetrated?
could we have penetrated?
could you have penetrated?
could they have penetrated? 	could I have been penetrating?
could you have been penetrating?
could she have been penetrating?
could we have been penetrating?
could you have been penetrating?
could they have been penetrating? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I penetrate?
couldn't you penetrate?
couldn't she penetrate?
couldn't we penetrate?
couldn't you penetrate?
couldn't they penetrate? 	couldn't I be penetrating?
couldn't you be penetrating?
couldn't she be penetrating?
couldn't we be penetrating?
couldn't you be penetrating?
couldn't they be penetrating? 	couldn't I have penetrated?
couldn't you have penetrated?
couldn't she have penetrated?
couldn't we have penetrated?
couldn't you have penetrated?
couldn't they have penetrated? 	couldn't I have been penetrating?
couldn't you have been penetrating?
couldn't she have been penetrating?
couldn't we have been penetrating?
couldn't you have been penetrating?
couldn't they have been penetrating?