Warning, this verb may not exist. Conjugation is given as example.
Affirmation
Simple form
I must laughter you must laughter she must laughter we must laughter you must laughter they must laughter
V-ing form
I must be laughtering you must be laughtering she must be laughtering we must be laughtering you must be laughtering they must be laughtering
Perfect
I must have laughtered you must have laughtered she must have laughtered we must have laughtered you must have laughtered they must have laughtered
V-ing perfect
I must have been laughtering you must have been laughtering she must have been laughtering we must have been laughtering you must have been laughtering they must have been laughtering
Negation
Simple form
I mustn't laughter you mustn't laughter she mustn't laughter we mustn't laughter you mustn't laughter they mustn't laughter
V-ing form
I mustn't be laughtering you mustn't be laughtering she mustn't be laughtering we mustn't be laughtering you mustn't be laughtering they mustn't be laughtering
Perfect
I mustn't have laughtered you mustn't have laughtered she mustn't have laughtered we mustn't have laughtered you mustn't have laughtered they mustn't have laughtered
V-ing perfect
I mustn't have been laughtering you mustn't have been laughtering she mustn't have been laughtering we mustn't have been laughtering you mustn't have been laughtering they mustn't have been laughtering
Interrogative form
Simple form
must I laughter? must you laughter? must she laughter? must we laughter? must you laughter? must they laughter?
V-ing form
must I be laughtering? must you be laughtering? must she be laughtering? must we be laughtering? must you be laughtering? must they be laughtering?
Perfect
must I have laughtered? must you have laughtered? must she have laughtered? must we have laughtered? must you have laughtered? must they have laughtered?
V-ing perfect
must I have been laughtering? must you have been laughtering? must she have been laughtering? must we have been laughtering? must you have been laughtering? must they have been laughtering?
Interro-negative form
Simple form
mustn't I laughter? mustn't you laughter? mustn't she laughter? mustn't we laughter? mustn't you laughter? mustn't they laughter?
V-ing form
mustn't I be laughtering? mustn't you be laughtering? mustn't she be laughtering? mustn't we be laughtering? mustn't you be laughtering? mustn't they be laughtering?
Perfect
mustn't I have laughtered? mustn't you have laughtered? mustn't she have laughtered? mustn't we have laughtered? mustn't you have laughtered? mustn't they have laughtered?
V-ing perfect
mustn't I have been laughtering? mustn't you have been laughtering? mustn't she have been laughtering? mustn't we have been laughtering? mustn't you have been laughtering? mustn't they have been laughtering?