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 mustn't countersink you mustn't countersink he mustn't countersink we mustn't countersink you mustn't countersink they mustn't countersink	I mustn't be countersinking you mustn't be countersinking he mustn't be countersinking we mustn't be countersinking you mustn't be countersinking they mustn't be countersinking
Perfect	V-ing perfect
I mustn't have countersunk you mustn't have countersunk he mustn't have countersunk we mustn't have countersunk you mustn't have countersunk they mustn't have countersunk	I mustn't have been countersinking you mustn't have been countersinking he mustn't have been countersinking we mustn't have been countersinking you mustn't have been countersinking they mustn't 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
mustn't I countersink? mustn't you countersink? mustn't he countersink? mustn't we countersink? mustn't you countersink? mustn't they countersink?	mustn't I be countersinking? mustn't you be countersinking? mustn't he be countersinking? mustn't we be countersinking? mustn't you be countersinking? mustn't they be countersinking?
Perfect	V-ing perfect
mustn't I have countersunk? mustn't you have countersunk? mustn't he have countersunk? mustn't we have countersunk? mustn't you have countersunk? mustn't they have countersunk?	mustn't I have been countersinking? mustn't you have been countersinking? mustn't he have been countersinking? mustn't we have been countersinking? mustn't you have been countersinking? mustn't they have been countersinking?