I must counter you must counter she must counter we must counter you must counter they must counter
V-ing form
I must be countering you must be countering she must be countering we must be countering you must be countering they must be countering
Perfect
I must have countered you must have countered she must have countered we must have countered you must have countered they must have countered
V-ing perfect
I must have been countering you must have been countering she must have been countering we must have been countering you must have been countering they must have been countering
Negation
Simple form
I mustn't counter you mustn't counter she mustn't counter we mustn't counter you mustn't counter they mustn't counter
V-ing form
I mustn't be countering you mustn't be countering she mustn't be countering we mustn't be countering you mustn't be countering they mustn't be countering
Perfect
I mustn't have countered you mustn't have countered she mustn't have countered we mustn't have countered you mustn't have countered they mustn't have countered
V-ing perfect
I mustn't have been countering you mustn't have been countering she mustn't have been countering we mustn't have been countering you mustn't have been countering they mustn't have been countering
Interrogative form
Simple form
must I counter? must you counter? must she counter? must we counter? must you counter? must they counter?
V-ing form
must I be countering? must you be countering? must she be countering? must we be countering? must you be countering? must they be countering?
Perfect
must I have countered? must you have countered? must she have countered? must we have countered? must you have countered? must they have countered?
V-ing perfect
must I have been countering? must you have been countering? must she have been countering? must we have been countering? must you have been countering? must they have been countering?
Interro-negative form
Simple form
mustn't I counter? mustn't you counter? mustn't she counter? mustn't we counter? mustn't you counter? mustn't they counter?
V-ing form
mustn't I be countering? mustn't you be countering? mustn't she be countering? mustn't we be countering? mustn't you be countering? mustn't they be countering?
Perfect
mustn't I have countered? mustn't you have countered? mustn't she have countered? mustn't we have countered? mustn't you have countered? mustn't they have countered?
V-ing perfect
mustn't I have been countering? mustn't you have been countering? mustn't she have been countering? mustn't we have been countering? mustn't you have been countering? mustn't they have been countering?