English verb conjugation
MUST COUNTERCHECK

Regular verb: countercheck - counterchecked - counterchecked

Affirmation

Simple form	V-ing form
I must countercheck you must countercheck she must countercheck we must countercheck you must countercheck they must countercheck	I must be counterchecking you must be counterchecking she must be counterchecking we must be counterchecking you must be counterchecking they must be counterchecking
Perfect	V-ing perfect
I must have counterchecked you must have counterchecked she must have counterchecked we must have counterchecked you must have counterchecked they must have counterchecked	I must have been counterchecking you must have been counterchecking she must have been counterchecking we must have been counterchecking you must have been counterchecking they must have been counterchecking

Negation

Simple form	V-ing form
I mustn't countercheck you mustn't countercheck she mustn't countercheck we mustn't countercheck you mustn't countercheck they mustn't countercheck	I mustn't be counterchecking you mustn't be counterchecking she mustn't be counterchecking we mustn't be counterchecking you mustn't be counterchecking they mustn't be counterchecking
Perfect	V-ing perfect
I mustn't have counterchecked you mustn't have counterchecked she mustn't have counterchecked we mustn't have counterchecked you mustn't have counterchecked they mustn't have counterchecked	I mustn't have been counterchecking you mustn't have been counterchecking she mustn't have been counterchecking we mustn't have been counterchecking you mustn't have been counterchecking they mustn't have been counterchecking

Interrogative form

Simple form	V-ing form
must I countercheck? must you countercheck? must she countercheck? must we countercheck? must you countercheck? must they countercheck?	must I be counterchecking? must you be counterchecking? must she be counterchecking? must we be counterchecking? must you be counterchecking? must they be counterchecking?
Perfect	V-ing perfect
must I have counterchecked? must you have counterchecked? must she have counterchecked? must we have counterchecked? must you have counterchecked? must they have counterchecked?	must I have been counterchecking? must you have been counterchecking? must she have been counterchecking? must we have been counterchecking? must you have been counterchecking? must they have been counterchecking?

Interro-negative form

Simple form	V-ing form
mustn't I countercheck? mustn't you countercheck? mustn't she countercheck? mustn't we countercheck? mustn't you countercheck? mustn't they countercheck?	mustn't I be counterchecking? mustn't you be counterchecking? mustn't she be counterchecking? mustn't we be counterchecking? mustn't you be counterchecking? mustn't they be counterchecking?
Perfect	V-ing perfect
mustn't I have counterchecked? mustn't you have counterchecked? mustn't she have counterchecked? mustn't we have counterchecked? mustn't you have counterchecked? mustn't they have counterchecked?	mustn't I have been counterchecking? mustn't you have been counterchecking? mustn't she have been counterchecking? mustn't we have been counterchecking? mustn't you have been counterchecking? mustn't they have been counterchecking?