I could nickel you could nickel he could nickel we could nickel you could nickel they could nickel
V-ing form
I could be nickelling you could be nickelling he could be nickelling we could be nickelling you could be nickelling they could be nickelling
Perfect
I could have nickelled you could have nickelled he could have nickelled we could have nickelled you could have nickelled they could have nickelled
V-ing perfect
I could have been nickelling you could have been nickelling he could have been nickelling we could have been nickelling you could have been nickelling they could have been nickelling
Negation
Simple form
I could not nickel you could not nickel he could not nickel we could not nickel you could not nickel they could not nickel
V-ing form
I could not be nickelling you could not be nickelling he could not be nickelling we could not be nickelling you could not be nickelling they could not be nickelling
Perfect
I could not have nickelled you could not have nickelled he could not have nickelled we could not have nickelled you could not have nickelled they could not have nickelled
V-ing perfect
I could not have been nickelling you could not have been nickelling he could not have been nickelling we could not have been nickelling you could not have been nickelling they could not have been nickelling
Interrogative form
Simple form
could I nickel? could you nickel? could he nickel? could we nickel? could you nickel? could they nickel?
V-ing form
could I be nickelling? could you be nickelling? could he be nickelling? could we be nickelling? could you be nickelling? could they be nickelling?
Perfect
could I have nickelled? could you have nickelled? could he have nickelled? could we have nickelled? could you have nickelled? could they have nickelled?
V-ing perfect
could I have been nickelling? could you have been nickelling? could he have been nickelling? could we have been nickelling? could you have been nickelling? could they have been nickelling?
Interro-negative form
Simple form
could I not nickel? could you not nickel? could he not nickel? could we not nickel? could you not nickel? could they not nickel?
V-ing form
could I not be nickelling? could you not be nickelling? could he not be nickelling? could we not be nickelling? could you not be nickelling? could they not be nickelling?
Perfect
could I not have nickelled? could you not have nickelled? could he not have nickelled? could we not have nickelled? could you not have nickelled? could they not have nickelled?
V-ing perfect
could I not have been nickelling? could you not have been nickelling? could he not have been nickelling? could we not have been nickelling? could you not have been nickelling? could they not have been nickelling?