I must countersink you must countersink he must countersink we must countersink you must countersink they must countersink
V-ing form
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
I must have countersunk you must have countersunk he must have countersunk we must have countersunk you must have countersunk they must have countersunk
V-ing perfect
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
I mustn't countersink you mustn't countersink he mustn't countersink we mustn't countersink you mustn't countersink they mustn't countersink
V-ing form
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
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
V-ing perfect
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
must I countersink? must you countersink? must he countersink? must we countersink? must you countersink? must they countersink?
V-ing form
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
must I have countersunk? must you have countersunk? must he have countersunk? must we have countersunk? must you have countersunk? must they have countersunk?
V-ing perfect
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
mustn't I countersink? mustn't you countersink? mustn't he countersink? mustn't we countersink? mustn't you countersink? mustn't they countersink?
V-ing form
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
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?
V-ing perfect
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?