English verb conjugation
MUST COUNTERSINK

Irregular verb: countersink - countersank - countersunk

Affirmation

Simple form	V-ing form
I must countersink you must countersink he must countersink we must countersink you must countersink they must countersink	I must be countersinking you must be countersinking he must be countersinking we must be countersinking you must be countersinking they must be countersinking
Perfect	V-ing perfect
I must have countersunk you must have countersunk he must have countersunk we must have countersunk you must have countersunk they must have countersunk	I must have been countersinking you must have been countersinking he must have been countersinking we must have been countersinking you must have been countersinking they must have been countersinking

Negation

Simple form	V-ing form
I must not countersink you must not countersink he must not countersink we must not countersink you must not countersink they must not countersink	I must not be countersinking you must not be countersinking he must not be countersinking we must not be countersinking you must not be countersinking they must not be countersinking
Perfect	V-ing perfect
I must not have countersunk you must not have countersunk he must not have countersunk we must not have countersunk you must not have countersunk they must not have countersunk	I must not have been countersinking you must not have been countersinking he must not have been countersinking we must not have been countersinking you must not have been countersinking they must not have been countersinking

Interrogative form

Simple form	V-ing form
must I countersink? must you countersink? must he countersink? must we countersink? must you countersink? must they countersink?	must I be countersinking? must you be countersinking? must he be countersinking? must we be countersinking? must you be countersinking? must they be countersinking?
Perfect	V-ing perfect
must I have countersunk? must you have countersunk? must he have countersunk? must we have countersunk? must you have countersunk? must they have countersunk?	must I have been countersinking? must you have been countersinking? must he have been countersinking? must we have been countersinking? must you have been countersinking? must they have been countersinking?

Interro-negative form

Simple form	V-ing form
must I not countersink? must you not countersink? must he not countersink? must we not countersink? must you not countersink? must they not countersink?	must I not be countersinking? must you not be countersinking? must he not be countersinking? must we not be countersinking? must you not be countersinking? must they not be countersinking?
Perfect	V-ing perfect
must I not have countersunk? must you not have countersunk? must he not have countersunk? must we not have countersunk? must you not have countersunk? must they not have countersunk?	must I not have been countersinking? must you not have been countersinking? must he not have been countersinking? must we not have been countersinking? must you not have been countersinking? must they not have been countersinking?