could shell
Regular verb: shell - shelled- shelled

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could shell
you could shell
she could shell
we could shell
you could shell
they could shell 	I could be shelling
you could be shelling
she could be shelling
we could be shelling
you could be shelling
they could be shelling	I could have shelled
you could have shelled
she could have shelled
we could have shelled
you could have shelled
they could have shelled	I could have been shelling
you could have been shelling
she could have been shelling
we could have been shelling
you could have been shelling
they could have been shelling	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I could not shell
you could not shell
she could not shell
we could not shell
you could not shell
they could not shell 	I could not be shelling
you could not be shelling
she could not be shelling
we could not be shelling
you could not be shelling
they could not be shelling	I could not have shelled
you could not have shelled
she could not have shelled
we could not have shelled
you could not have shelled
they could not have shelled	I could not have been shelling
you could not have been shelling
she could not have been shelling
we could not have been shelling
you could not have been shelling
they could not have been shelling	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I shell?
could you shell?
could she shell?
could we shell?
could you shell?
could they shell? 	could I be shelling?
could you be shelling?
could she be shelling?
could we be shelling?
could you be shelling?
could they be shelling? 	could I have shelled?
could you have shelled?
could she have shelled?
could we have shelled?
could you have shelled?
could they have shelled? 	could I have been shelling?
could you have been shelling?
could she have been shelling?
could we have been shelling?
could you have been shelling?
could they have been shelling? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
could I not shell?
could you not shell?
could she not shell?
could we not shell?
could you not shell?
could they not shell? 	could I not be shelling?
could you not be shelling?
could she not be shelling?
could we not be shelling?
could you not be shelling?
could they not be shelling? 	could I not have shelled?
could you not have shelled?
could she not have shelled?
could we not have shelled?
could you not have shelled?
could they not have shelled? 	could I not have been shelling?
could you not have been shelling?
could she not have been shelling?
could we not have been shelling?
could you not have been shelling?
could they not have been shelling?