I must spy you must spy he must spy we must spy you must spy they must spy
V-ing form
I must be spying you must be spying he must be spying we must be spying you must be spying they must be spying
Perfect
I must have spied you must have spied he must have spied we must have spied you must have spied they must have spied
V-ing perfect
I must have been spying you must have been spying he must have been spying we must have been spying you must have been spying they must have been spying
Negation
Simple form
I must not spy you must not spy he must not spy we must not spy you must not spy they must not spy
V-ing form
I must not be spying you must not be spying he must not be spying we must not be spying you must not be spying they must not be spying
Perfect
I must not have spied you must not have spied he must not have spied we must not have spied you must not have spied they must not have spied
V-ing perfect
I must not have been spying you must not have been spying he must not have been spying we must not have been spying you must not have been spying they must not have been spying
Interrogative form
Simple form
must I spy? must you spy? must he spy? must we spy? must you spy? must they spy?
V-ing form
must I be spying? must you be spying? must he be spying? must we be spying? must you be spying? must they be spying?
Perfect
must I have spied? must you have spied? must he have spied? must we have spied? must you have spied? must they have spied?
V-ing perfect
must I have been spying? must you have been spying? must he have been spying? must we have been spying? must you have been spying? must they have been spying?
Interro-negative form
Simple form
must I not spy? must you not spy? must he not spy? must we not spy? must you not spy? must they not spy?
V-ing form
must I not be spying? must you not be spying? must he not be spying? must we not be spying? must you not be spying? must they not be spying?
Perfect
must I not have spied? must you not have spied? must he not have spied? must we not have spied? must you not have spied? must they not have spied?
V-ing perfect
must I not have been spying? must you not have been spying? must he not have been spying? must we not have been spying? must you not have been spying? must they not have been spying?