could twinkle
Regular verb: twinkle - twinkled- twinkled

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could twinkle
you could twinkle
she could twinkle
we could twinkle
you could twinkle
they could twinkle 	I could be twinkling
you could be twinkling
she could be twinkling
we could be twinkling
you could be twinkling
they could be twinkling	I could have twinkled
you could have twinkled
she could have twinkled
we could have twinkled
you could have twinkled
they could have twinkled	I could have been twinkling
you could have been twinkling
she could have been twinkling
we could have been twinkling
you could have been twinkling
they could have been twinkling	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't twinkle
you couldn't twinkle
she couldn't twinkle
we couldn't twinkle
you couldn't twinkle
they couldn't twinkle 	I couldn't be twinkling
you couldn't be twinkling
she couldn't be twinkling
we couldn't be twinkling
you couldn't be twinkling
they couldn't be twinkling	I couldn't have twinkled
you couldn't have twinkled
she couldn't have twinkled
we couldn't have twinkled
you couldn't have twinkled
they couldn't have twinkled	I couldn't have been twinkling
you couldn't have been twinkling
she couldn't have been twinkling
we couldn't have been twinkling
you couldn't have been twinkling
they couldn't have been twinkling	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I twinkle?
could you twinkle?
could she twinkle?
could we twinkle?
could you twinkle?
could they twinkle? 	could I be twinkling?
could you be twinkling?
could she be twinkling?
could we be twinkling?
could you be twinkling?
could they be twinkling? 	could I have twinkled?
could you have twinkled?
could she have twinkled?
could we have twinkled?
could you have twinkled?
could they have twinkled? 	could I have been twinkling?
could you have been twinkling?
could she have been twinkling?
could we have been twinkling?
could you have been twinkling?
could they have been twinkling? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I twinkle?
couldn't you twinkle?
couldn't she twinkle?
couldn't we twinkle?
couldn't you twinkle?
couldn't they twinkle? 	couldn't I be twinkling?
couldn't you be twinkling?
couldn't she be twinkling?
couldn't we be twinkling?
couldn't you be twinkling?
couldn't they be twinkling? 	couldn't I have twinkled?
couldn't you have twinkled?
couldn't she have twinkled?
couldn't we have twinkled?
couldn't you have twinkled?
couldn't they have twinkled? 	couldn't I have been twinkling?
couldn't you have been twinkling?
couldn't she have been twinkling?
couldn't we have been twinkling?
couldn't you have been twinkling?
couldn't they have been twinkling?