I must squint you must squint he must squint we must squint you must squint they must squint
V-ing form
I must be squinting you must be squinting he must be squinting we must be squinting you must be squinting they must be squinting
Perfect
I must have squinted you must have squinted he must have squinted we must have squinted you must have squinted they must have squinted
V-ing perfect
I must have been squinting you must have been squinting he must have been squinting we must have been squinting you must have been squinting they must have been squinting
Negation
Simple form
I must not squint you must not squint he must not squint we must not squint you must not squint they must not squint
V-ing form
I must not be squinting you must not be squinting he must not be squinting we must not be squinting you must not be squinting they must not be squinting
Perfect
I must not have squinted you must not have squinted he must not have squinted we must not have squinted you must not have squinted they must not have squinted
V-ing perfect
I must not have been squinting you must not have been squinting he must not have been squinting we must not have been squinting you must not have been squinting they must not have been squinting
Interrogative form
Simple form
must I squint? must you squint? must he squint? must we squint? must you squint? must they squint?
V-ing form
must I be squinting? must you be squinting? must he be squinting? must we be squinting? must you be squinting? must they be squinting?
Perfect
must I have squinted? must you have squinted? must he have squinted? must we have squinted? must you have squinted? must they have squinted?
V-ing perfect
must I have been squinting? must you have been squinting? must he have been squinting? must we have been squinting? must you have been squinting? must they have been squinting?
Interro-negative form
Simple form
must I not squint? must you not squint? must he not squint? must we not squint? must you not squint? must they not squint?
V-ing form
must I not be squinting? must you not be squinting? must he not be squinting? must we not be squinting? must you not be squinting? must they not be squinting?
Perfect
must I not have squinted? must you not have squinted? must he not have squinted? must we not have squinted? must you not have squinted? must they not have squinted?
V-ing perfect
must I not have been squinting? must you not have been squinting? must he not have been squinting? must we not have been squinting? must you not have been squinting? must they not have been squinting?