English verb conjugation
COULD SKULK

Regular verb: skulk - skulked - skulked

Affirmation

Simple form	V-ing form
I could skulk you could skulk he could skulk we could skulk you could skulk they could skulk	I could be skulking you could be skulking he could be skulking we could be skulking you could be skulking they could be skulking
Perfect	V-ing perfect
I could have skulked you could have skulked he could have skulked we could have skulked you could have skulked they could have skulked	I could have been skulking you could have been skulking he could have been skulking we could have been skulking you could have been skulking they could have been skulking

Negation

Simple form	V-ing form
I could not skulk you could not skulk he could not skulk we could not skulk you could not skulk they could not skulk	I could not be skulking you could not be skulking he could not be skulking we could not be skulking you could not be skulking they could not be skulking
Perfect	V-ing perfect
I could not have skulked you could not have skulked he could not have skulked we could not have skulked you could not have skulked they could not have skulked	I could not have been skulking you could not have been skulking he could not have been skulking we could not have been skulking you could not have been skulking they could not have been skulking

Interrogative form

Simple form	V-ing form
could I skulk? could you skulk? could he skulk? could we skulk? could you skulk? could they skulk?	could I be skulking? could you be skulking? could he be skulking? could we be skulking? could you be skulking? could they be skulking?
Perfect	V-ing perfect
could I have skulked? could you have skulked? could he have skulked? could we have skulked? could you have skulked? could they have skulked?	could I have been skulking? could you have been skulking? could he have been skulking? could we have been skulking? could you have been skulking? could they have been skulking?

Interro-negative form

Simple form	V-ing form
could I not skulk? could you not skulk? could he not skulk? could we not skulk? could you not skulk? could they not skulk?	could I not be skulking? could you not be skulking? could he not be skulking? could we not be skulking? could you not be skulking? could they not be skulking?
Perfect	V-ing perfect
could I not have skulked? could you not have skulked? could he not have skulked? could we not have skulked? could you not have skulked? could they not have skulked?	could I not have been skulking? could you not have been skulking? could he not have been skulking? could we not have been skulking? could you not have been skulking? could they not have been skulking?