English verb conjugation
MUST SUSTAIN

Regular verb: sustain - sustained - sustained

Affirmation

Simple form	V-ing form
I must sustain you must sustain he must sustain we must sustain you must sustain they must sustain	I must be sustaining you must be sustaining he must be sustaining we must be sustaining you must be sustaining they must be sustaining
Perfect	V-ing perfect
I must have sustained you must have sustained he must have sustained we must have sustained you must have sustained they must have sustained	I must have been sustaining you must have been sustaining he must have been sustaining we must have been sustaining you must have been sustaining they must have been sustaining

Negation

Simple form	V-ing form
I must not sustain you must not sustain he must not sustain we must not sustain you must not sustain they must not sustain	I must not be sustaining you must not be sustaining he must not be sustaining we must not be sustaining you must not be sustaining they must not be sustaining
Perfect	V-ing perfect
I must not have sustained you must not have sustained he must not have sustained we must not have sustained you must not have sustained they must not have sustained	I must not have been sustaining you must not have been sustaining he must not have been sustaining we must not have been sustaining you must not have been sustaining they must not have been sustaining

Interrogative form

Simple form	V-ing form
must I sustain? must you sustain? must he sustain? must we sustain? must you sustain? must they sustain?	must I be sustaining? must you be sustaining? must he be sustaining? must we be sustaining? must you be sustaining? must they be sustaining?
Perfect	V-ing perfect
must I have sustained? must you have sustained? must he have sustained? must we have sustained? must you have sustained? must they have sustained?	must I have been sustaining? must you have been sustaining? must he have been sustaining? must we have been sustaining? must you have been sustaining? must they have been sustaining?

Interro-negative form

Simple form	V-ing form
must I not sustain? must you not sustain? must he not sustain? must we not sustain? must you not sustain? must they not sustain?	must I not be sustaining? must you not be sustaining? must he not be sustaining? must we not be sustaining? must you not be sustaining? must they not be sustaining?
Perfect	V-ing perfect
must I not have sustained? must you not have sustained? must he not have sustained? must we not have sustained? must you not have sustained? must they not have sustained?	must I not have been sustaining? must you not have been sustaining? must he not have been sustaining? must we not have been sustaining? must you not have been sustaining? must they not have been sustaining?