English verb conjugation
MUST COUNTERCHECK

Regular verb: countercheck - counterchecked - counterchecked

Affirmation

Simple form	V-ing form
I must countercheck you must countercheck he must countercheck we must countercheck you must countercheck they must countercheck	I must be counterchecking you must be counterchecking he 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 he 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 he 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 must not countercheck you must not countercheck he must not countercheck we must not countercheck you must not countercheck they must not countercheck	I must not be counterchecking you must not be counterchecking he must not be counterchecking we must not be counterchecking you must not be counterchecking they must not be counterchecking
Perfect	V-ing perfect
I must not have counterchecked you must not have counterchecked he must not have counterchecked we must not have counterchecked you must not have counterchecked they must not have counterchecked	I must not have been counterchecking you must not have been counterchecking he must not have been counterchecking we must not have been counterchecking you must not have been counterchecking they must not have been counterchecking

Interrogative form

Simple form	V-ing form
must I countercheck? must you countercheck? must he countercheck? must we countercheck? must you countercheck? must they countercheck?	must I be counterchecking? must you be counterchecking? must he 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 he 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 he 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
must I not countercheck? must you not countercheck? must he not countercheck? must we not countercheck? must you not countercheck? must they not countercheck?	must I not be counterchecking? must you not be counterchecking? must he not be counterchecking? must we not be counterchecking? must you not be counterchecking? must they not be counterchecking?
Perfect	V-ing perfect
must I not have counterchecked? must you not have counterchecked? must he not have counterchecked? must we not have counterchecked? must you not have counterchecked? must they not have counterchecked?	must I not have been counterchecking? must you not have been counterchecking? must he not have been counterchecking? must we not have been counterchecking? must you not have been counterchecking? must they not have been counterchecking?