could curb
Regular verb: curb - curbed- curbed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could curb
you could curb
he could curb
we could curb
you could curb
they could curb 	I could be curbing
you could be curbing
he could be curbing
we could be curbing
you could be curbing
they could be curbing	I could have curbed
you could have curbed
he could have curbed
we could have curbed
you could have curbed
they could have curbed	I could have been curbing
you could have been curbing
he could have been curbing
we could have been curbing
you could have been curbing
they could have been curbing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't curb
you couldn't curb
he couldn't curb
we couldn't curb
you couldn't curb
they couldn't curb 	I couldn't be curbing
you couldn't be curbing
he couldn't be curbing
we couldn't be curbing
you couldn't be curbing
they couldn't be curbing	I couldn't have curbed
you couldn't have curbed
he couldn't have curbed
we couldn't have curbed
you couldn't have curbed
they couldn't have curbed	I couldn't have been curbing
you couldn't have been curbing
he couldn't have been curbing
we couldn't have been curbing
you couldn't have been curbing
they couldn't have been curbing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I curb?
could you curb?
could he curb?
could we curb?
could you curb?
could they curb? 	could I be curbing?
could you be curbing?
could he be curbing?
could we be curbing?
could you be curbing?
could they be curbing? 	could I have curbed?
could you have curbed?
could he have curbed?
could we have curbed?
could you have curbed?
could they have curbed? 	could I have been curbing?
could you have been curbing?
could he have been curbing?
could we have been curbing?
could you have been curbing?
could they have been curbing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I curb?
couldn't you curb?
couldn't he curb?
couldn't we curb?
couldn't you curb?
couldn't they curb? 	couldn't I be curbing?
couldn't you be curbing?
couldn't he be curbing?
couldn't we be curbing?
couldn't you be curbing?
couldn't they be curbing? 	couldn't I have curbed?
couldn't you have curbed?
couldn't he have curbed?
couldn't we have curbed?
couldn't you have curbed?
couldn't they have curbed? 	couldn't I have been curbing?
couldn't you have been curbing?
couldn't he have been curbing?
couldn't we have been curbing?
couldn't you have been curbing?
couldn't they have been curbing?