English verb conjugation
MUST SKULK

Regular verb: skulk - skulked - skulked

Affirmation

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

Negation

Simple form	V-ing form
I mustn't skulk you mustn't skulk he mustn't skulk we mustn't skulk you mustn't skulk they mustn't skulk	I mustn't be skulking you mustn't be skulking he mustn't be skulking we mustn't be skulking you mustn't be skulking they mustn't be skulking
Perfect	V-ing perfect
I mustn't have skulked you mustn't have skulked he mustn't have skulked we mustn't have skulked you mustn't have skulked they mustn't have skulked	I mustn't have been skulking you mustn't have been skulking he mustn't have been skulking we mustn't have been skulking you mustn't have been skulking they mustn't have been skulking

Interrogative form

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

Interro-negative form

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