English verb conjugation
COULD SHELL

Regular verb: shell - shelled - shelled

Affirmation

Simple form	V-ing form
I could shell you could shell he could shell we could shell you could shell they could shell	I could be shelling you could be shelling he could be shelling we could be shelling you could be shelling they could be shelling
Perfect	V-ing perfect
I could have shelled you could have shelled he 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 he 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
I couldn't shell you couldn't shell he couldn't shell we couldn't shell you couldn't shell they couldn't shell	I couldn't be shelling you couldn't be shelling he couldn't be shelling we couldn't be shelling you couldn't be shelling they couldn't be shelling
Perfect	V-ing perfect
I couldn't have shelled you couldn't have shelled he couldn't have shelled we couldn't have shelled you couldn't have shelled they couldn't have shelled	I couldn't have been shelling you couldn't have been shelling he couldn't have been shelling we couldn't have been shelling you couldn't have been shelling they couldn't have been shelling

Interrogative form

Simple form	V-ing form
could I shell? could you shell? could he shell? could we shell? could you shell? could they shell?	could I be shelling? could you be shelling? could he be shelling? could we be shelling? could you be shelling? could they be shelling?
Perfect	V-ing perfect
could I have shelled? could you have shelled? could he 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 he 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
couldn't I shell? couldn't you shell? couldn't he shell? couldn't we shell? couldn't you shell? couldn't they shell?	couldn't I be shelling? couldn't you be shelling? couldn't he be shelling? couldn't we be shelling? couldn't you be shelling? couldn't they be shelling?
Perfect	V-ing perfect
couldn't I have shelled? couldn't you have shelled? couldn't he have shelled? couldn't we have shelled? couldn't you have shelled? couldn't they have shelled?	couldn't I have been shelling? couldn't you have been shelling? couldn't he have been shelling? couldn't we have been shelling? couldn't you have been shelling? couldn't they have been shelling?