could thwack
Regular verb: thwack - thwacked- thwacked

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could thwack
you could thwack
she could thwack
we could thwack
you could thwack
they could thwack 	I could be thwacking
you could be thwacking
she could be thwacking
we could be thwacking
you could be thwacking
they could be thwacking	I could have thwacked
you could have thwacked
she could have thwacked
we could have thwacked
you could have thwacked
they could have thwacked	I could have been thwacking
you could have been thwacking
she could have been thwacking
we could have been thwacking
you could have been thwacking
they could have been thwacking	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not thwack
you could not thwack
she could not thwack
we could not thwack
you could not thwack
they could not thwack 	I could not be thwacking
you could not be thwacking
she could not be thwacking
we could not be thwacking
you could not be thwacking
they could not be thwacking	I could not have thwacked
you could not have thwacked
she could not have thwacked
we could not have thwacked
you could not have thwacked
they could not have thwacked	I could not have been thwacking
you could not have been thwacking
she could not have been thwacking
we could not have been thwacking
you could not have been thwacking
they could not have been thwacking	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I thwack?
could you thwack?
could she thwack?
could we thwack?
could you thwack?
could they thwack? 	could I be thwacking?
could you be thwacking?
could she be thwacking?
could we be thwacking?
could you be thwacking?
could they be thwacking? 	could I have thwacked?
could you have thwacked?
could she have thwacked?
could we have thwacked?
could you have thwacked?
could they have thwacked? 	could I have been thwacking?
could you have been thwacking?
could she have been thwacking?
could we have been thwacking?
could you have been thwacking?
could they have been thwacking? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not thwack?
could you not thwack?
could she not thwack?
could we not thwack?
could you not thwack?
could they not thwack? 	could I not be thwacking?
could you not be thwacking?
could she not be thwacking?
could we not be thwacking?
could you not be thwacking?
could they not be thwacking? 	could I not have thwacked?
could you not have thwacked?
could she not have thwacked?
could we not have thwacked?
could you not have thwacked?
could they not have thwacked? 	could I not have been thwacking?
could you not have been thwacking?
could she not have been thwacking?
could we not have been thwacking?
could you not have been thwacking?
could they not have been thwacking?