could crack
Regular verb: crack - cracked- cracked

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could crack
you could crack
she could crack
we could crack
you could crack
they could crack 	I could be cracking
you could be cracking
she could be cracking
we could be cracking
you could be cracking
they could be cracking	I could have cracked
you could have cracked
she could have cracked
we could have cracked
you could have cracked
they could have cracked	I could have been cracking
you could have been cracking
she could have been cracking
we could have been cracking
you could have been cracking
they could have been cracking	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not crack
you could not crack
she could not crack
we could not crack
you could not crack
they could not crack 	I could not be cracking
you could not be cracking
she could not be cracking
we could not be cracking
you could not be cracking
they could not be cracking	I could not have cracked
you could not have cracked
she could not have cracked
we could not have cracked
you could not have cracked
they could not have cracked	I could not have been cracking
you could not have been cracking
she could not have been cracking
we could not have been cracking
you could not have been cracking
they could not have been cracking	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I crack?
could you crack?
could she crack?
could we crack?
could you crack?
could they crack? 	could I be cracking?
could you be cracking?
could she be cracking?
could we be cracking?
could you be cracking?
could they be cracking? 	could I have cracked?
could you have cracked?
could she have cracked?
could we have cracked?
could you have cracked?
could they have cracked? 	could I have been cracking?
could you have been cracking?
could she have been cracking?
could we have been cracking?
could you have been cracking?
could they have been cracking? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not crack?
could you not crack?
could she not crack?
could we not crack?
could you not crack?
could they not crack? 	could I not be cracking?
could you not be cracking?
could she not be cracking?
could we not be cracking?
could you not be cracking?
could they not be cracking? 	could I not have cracked?
could you not have cracked?
could she not have cracked?
could we not have cracked?
could you not have cracked?
could they not have cracked? 	could I not have been cracking?
could you not have been cracking?
could she not have been cracking?
could we not have been cracking?
could you not have been cracking?
could they not have been cracking?