could stimulate
Regular verb: stimulate - stimulated- stimulated

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could stimulate
you could stimulate
she could stimulate
we could stimulate
you could stimulate
they could stimulate 	I could be stimulating
you could be stimulating
she could be stimulating
we could be stimulating
you could be stimulating
they could be stimulating	I could have stimulated
you could have stimulated
she could have stimulated
we could have stimulated
you could have stimulated
they could have stimulated	I could have been stimulating
you could have been stimulating
she could have been stimulating
we could have been stimulating
you could have been stimulating
they could have been stimulating	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't stimulate
you couldn't stimulate
she couldn't stimulate
we couldn't stimulate
you couldn't stimulate
they couldn't stimulate 	I couldn't be stimulating
you couldn't be stimulating
she couldn't be stimulating
we couldn't be stimulating
you couldn't be stimulating
they couldn't be stimulating	I couldn't have stimulated
you couldn't have stimulated
she couldn't have stimulated
we couldn't have stimulated
you couldn't have stimulated
they couldn't have stimulated	I couldn't have been stimulating
you couldn't have been stimulating
she couldn't have been stimulating
we couldn't have been stimulating
you couldn't have been stimulating
they couldn't have been stimulating	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I stimulate?
could you stimulate?
could she stimulate?
could we stimulate?
could you stimulate?
could they stimulate? 	could I be stimulating?
could you be stimulating?
could she be stimulating?
could we be stimulating?
could you be stimulating?
could they be stimulating? 	could I have stimulated?
could you have stimulated?
could she have stimulated?
could we have stimulated?
could you have stimulated?
could they have stimulated? 	could I have been stimulating?
could you have been stimulating?
could she have been stimulating?
could we have been stimulating?
could you have been stimulating?
could they have been stimulating? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I stimulate?
couldn't you stimulate?
couldn't she stimulate?
couldn't we stimulate?
couldn't you stimulate?
couldn't they stimulate? 	couldn't I be stimulating?
couldn't you be stimulating?
couldn't she be stimulating?
couldn't we be stimulating?
couldn't you be stimulating?
couldn't they be stimulating? 	couldn't I have stimulated?
couldn't you have stimulated?
couldn't she have stimulated?
couldn't we have stimulated?
couldn't you have stimulated?
couldn't they have stimulated? 	couldn't I have been stimulating?
couldn't you have been stimulating?
couldn't she have been stimulating?
couldn't we have been stimulating?
couldn't you have been stimulating?
couldn't they have been stimulating?