could crackle
Regular verb: crackle - crackled- crackled

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could crackle
you could crackle
he could crackle
we could crackle
you could crackle
they could crackle 	I could be crackling
you could be crackling
he could be crackling
we could be crackling
you could be crackling
they could be crackling	I could have crackled
you could have crackled
he could have crackled
we could have crackled
you could have crackled
they could have crackled	I could have been crackling
you could have been crackling
he could have been crackling
we could have been crackling
you could have been crackling
they could have been crackling	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I couldn't crackle
you couldn't crackle
he couldn't crackle
we couldn't crackle
you couldn't crackle
they couldn't crackle 	I couldn't be crackling
you couldn't be crackling
he couldn't be crackling
we couldn't be crackling
you couldn't be crackling
they couldn't be crackling	I couldn't have crackled
you couldn't have crackled
he couldn't have crackled
we couldn't have crackled
you couldn't have crackled
they couldn't have crackled	I couldn't have been crackling
you couldn't have been crackling
he couldn't have been crackling
we couldn't have been crackling
you couldn't have been crackling
they couldn't have been crackling	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I crackle?
could you crackle?
could he crackle?
could we crackle?
could you crackle?
could they crackle? 	could I be crackling?
could you be crackling?
could he be crackling?
could we be crackling?
could you be crackling?
could they be crackling? 	could I have crackled?
could you have crackled?
could he have crackled?
could we have crackled?
could you have crackled?
could they have crackled? 	could I have been crackling?
could you have been crackling?
could he have been crackling?
could we have been crackling?
could you have been crackling?
could they have been crackling? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
couldn't I crackle?
couldn't you crackle?
couldn't he crackle?
couldn't we crackle?
couldn't you crackle?
couldn't they crackle? 	couldn't I be crackling?
couldn't you be crackling?
couldn't he be crackling?
couldn't we be crackling?
couldn't you be crackling?
couldn't they be crackling? 	couldn't I have crackled?
couldn't you have crackled?
couldn't he have crackled?
couldn't we have crackled?
couldn't you have crackled?
couldn't they have crackled? 	couldn't I have been crackling?
couldn't you have been crackling?
couldn't he have been crackling?
couldn't we have been crackling?
couldn't you have been crackling?
couldn't they have been crackling?