I must couple you must couple he must couple we must couple you must couple they must couple
V-ing form
I must be coupling you must be coupling he must be coupling we must be coupling you must be coupling they must be coupling
Perfect
I must have coupled you must have coupled he must have coupled we must have coupled you must have coupled they must have coupled
V-ing perfect
I must have been coupling you must have been coupling he must have been coupling we must have been coupling you must have been coupling they must have been coupling
Negation
Simple form
I mustn't couple you mustn't couple he mustn't couple we mustn't couple you mustn't couple they mustn't couple
V-ing form
I mustn't be coupling you mustn't be coupling he mustn't be coupling we mustn't be coupling you mustn't be coupling they mustn't be coupling
Perfect
I mustn't have coupled you mustn't have coupled he mustn't have coupled we mustn't have coupled you mustn't have coupled they mustn't have coupled
V-ing perfect
I mustn't have been coupling you mustn't have been coupling he mustn't have been coupling we mustn't have been coupling you mustn't have been coupling they mustn't have been coupling
Interrogative form
Simple form
must I couple? must you couple? must he couple? must we couple? must you couple? must they couple?
V-ing form
must I be coupling? must you be coupling? must he be coupling? must we be coupling? must you be coupling? must they be coupling?
Perfect
must I have coupled? must you have coupled? must he have coupled? must we have coupled? must you have coupled? must they have coupled?
V-ing perfect
must I have been coupling? must you have been coupling? must he have been coupling? must we have been coupling? must you have been coupling? must they have been coupling?
Interro-negative form
Simple form
mustn't I couple? mustn't you couple? mustn't he couple? mustn't we couple? mustn't you couple? mustn't they couple?
V-ing form
mustn't I be coupling? mustn't you be coupling? mustn't he be coupling? mustn't we be coupling? mustn't you be coupling? mustn't they be coupling?
Perfect
mustn't I have coupled? mustn't you have coupled? mustn't he have coupled? mustn't we have coupled? mustn't you have coupled? mustn't they have coupled?
V-ing perfect
mustn't I have been coupling? mustn't you have been coupling? mustn't he have been coupling? mustn't we have been coupling? mustn't you have been coupling? mustn't they have been coupling?