could pierce
Regular verb: pierce - pierced- pierced

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could pierce
you could pierce
she could pierce
we could pierce
you could pierce
they could pierce 	I could be piercing
you could be piercing
she could be piercing
we could be piercing
you could be piercing
they could be piercing	I could have pierced
you could have pierced
she could have pierced
we could have pierced
you could have pierced
they could have pierced	I could have been piercing
you could have been piercing
she could have been piercing
we could have been piercing
you could have been piercing
they could have been piercing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not pierce
you could not pierce
she could not pierce
we could not pierce
you could not pierce
they could not pierce 	I could not be piercing
you could not be piercing
she could not be piercing
we could not be piercing
you could not be piercing
they could not be piercing	I could not have pierced
you could not have pierced
she could not have pierced
we could not have pierced
you could not have pierced
they could not have pierced	I could not have been piercing
you could not have been piercing
she could not have been piercing
we could not have been piercing
you could not have been piercing
they could not have been piercing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I pierce?
could you pierce?
could she pierce?
could we pierce?
could you pierce?
could they pierce? 	could I be piercing?
could you be piercing?
could she be piercing?
could we be piercing?
could you be piercing?
could they be piercing? 	could I have pierced?
could you have pierced?
could she have pierced?
could we have pierced?
could you have pierced?
could they have pierced? 	could I have been piercing?
could you have been piercing?
could she have been piercing?
could we have been piercing?
could you have been piercing?
could they have been piercing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not pierce?
could you not pierce?
could she not pierce?
could we not pierce?
could you not pierce?
could they not pierce? 	could I not be piercing?
could you not be piercing?
could she not be piercing?
could we not be piercing?
could you not be piercing?
could they not be piercing? 	could I not have pierced?
could you not have pierced?
could she not have pierced?
could we not have pierced?
could you not have pierced?
could they not have pierced? 	could I not have been piercing?
could you not have been piercing?
could she not have been piercing?
could we not have been piercing?
could you not have been piercing?
could they not have been piercing?