could experiment
Regular verb: experiment - experimented- experimented

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could experiment
you could experiment
he could experiment
we could experiment
you could experiment
they could experiment 	I could be experimenting
you could be experimenting
he could be experimenting
we could be experimenting
you could be experimenting
they could be experimenting	I could have experimented
you could have experimented
he could have experimented
we could have experimented
you could have experimented
they could have experimented	I could have been experimenting
you could have been experimenting
he could have been experimenting
we could have been experimenting
you could have been experimenting
they could have been experimenting	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't experiment
you couldn't experiment
he couldn't experiment
we couldn't experiment
you couldn't experiment
they couldn't experiment 	I couldn't be experimenting
you couldn't be experimenting
he couldn't be experimenting
we couldn't be experimenting
you couldn't be experimenting
they couldn't be experimenting	I couldn't have experimented
you couldn't have experimented
he couldn't have experimented
we couldn't have experimented
you couldn't have experimented
they couldn't have experimented	I couldn't have been experimenting
you couldn't have been experimenting
he couldn't have been experimenting
we couldn't have been experimenting
you couldn't have been experimenting
they couldn't have been experimenting	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I experiment?
could you experiment?
could he experiment?
could we experiment?
could you experiment?
could they experiment? 	could I be experimenting?
could you be experimenting?
could he be experimenting?
could we be experimenting?
could you be experimenting?
could they be experimenting? 	could I have experimented?
could you have experimented?
could he have experimented?
could we have experimented?
could you have experimented?
could they have experimented? 	could I have been experimenting?
could you have been experimenting?
could he have been experimenting?
could we have been experimenting?
could you have been experimenting?
could they have been experimenting? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I experiment?
couldn't you experiment?
couldn't he experiment?
couldn't we experiment?
couldn't you experiment?
couldn't they experiment? 	couldn't I be experimenting?
couldn't you be experimenting?
couldn't he be experimenting?
couldn't we be experimenting?
couldn't you be experimenting?
couldn't they be experimenting? 	couldn't I have experimented?
couldn't you have experimented?
couldn't he have experimented?
couldn't we have experimented?
couldn't you have experimented?
couldn't they have experimented? 	couldn't I have been experimenting?
couldn't you have been experimenting?
couldn't he have been experimenting?
couldn't we have been experimenting?
couldn't you have been experimenting?
couldn't they have been experimenting?