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 couldn't thwack
you couldn't thwack
she couldn't thwack
we couldn't thwack
you couldn't thwack
they couldn't thwack 	I couldn't be thwacking
you couldn't be thwacking
she couldn't be thwacking
we couldn't be thwacking
you couldn't be thwacking
they couldn't be thwacking	I couldn't have thwacked
you couldn't have thwacked
she couldn't have thwacked
we couldn't have thwacked
you couldn't have thwacked
they couldn't have thwacked	I couldn't have been thwacking
you couldn't have been thwacking
she couldn't have been thwacking
we couldn't have been thwacking
you couldn't have been thwacking
they couldn't 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 	
couldn't I thwack?
couldn't you thwack?
couldn't she thwack?
couldn't we thwack?
couldn't you thwack?
couldn't they thwack? 	couldn't I be thwacking?
couldn't you be thwacking?
couldn't she be thwacking?
couldn't we be thwacking?
couldn't you be thwacking?
couldn't they be thwacking? 	couldn't I have thwacked?
couldn't you have thwacked?
couldn't she have thwacked?
couldn't we have thwacked?
couldn't you have thwacked?
couldn't they have thwacked? 	couldn't I have been thwacking?
couldn't you have been thwacking?
couldn't she have been thwacking?
couldn't we have been thwacking?
couldn't you have been thwacking?
couldn't they have been thwacking?