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 couldn't skulk you couldn't skulk he couldn't skulk we couldn't skulk you couldn't skulk they couldn't skulk	I couldn't be skulking you couldn't be skulking he couldn't be skulking we couldn't be skulking you couldn't be skulking they couldn't be skulking
Perfect	V-ing perfect
I couldn't have skulked you couldn't have skulked he couldn't have skulked we couldn't have skulked you couldn't have skulked they couldn't have skulked	I couldn't have been skulking you couldn't have been skulking he couldn't have been skulking we couldn't have been skulking you couldn't have been skulking they couldn't 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
couldn't I skulk? couldn't you skulk? couldn't he skulk? couldn't we skulk? couldn't you skulk? couldn't they skulk?	couldn't I be skulking? couldn't you be skulking? couldn't he be skulking? couldn't we be skulking? couldn't you be skulking? couldn't they be skulking?
Perfect	V-ing perfect
couldn't I have skulked? couldn't you have skulked? couldn't he have skulked? couldn't we have skulked? couldn't you have skulked? couldn't they have skulked?	couldn't I have been skulking? couldn't you have been skulking? couldn't he have been skulking? couldn't we have been skulking? couldn't you have been skulking? couldn't they have been skulking?