I must spit you must spit she must spit we must spit you must spit they must spit
V-ing form
I must be spitting you must be spitting she must be spitting we must be spitting you must be spitting they must be spitting
Perfect
I must have spit you must have spit she must have spit we must have spit you must have spit they must have spit
V-ing perfect
I must have been spitting you must have been spitting she must have been spitting we must have been spitting you must have been spitting they must have been spitting
Negation
Simple form
I must not spit you must not spit she must not spit we must not spit you must not spit they must not spit
V-ing form
I must not be spitting you must not be spitting she must not be spitting we must not be spitting you must not be spitting they must not be spitting
Perfect
I must not have spit you must not have spit she must not have spit we must not have spit you must not have spit they must not have spit
V-ing perfect
I must not have been spitting you must not have been spitting she must not have been spitting we must not have been spitting you must not have been spitting they must not have been spitting
Interrogative form
Simple form
must I spit? must you spit? must she spit? must we spit? must you spit? must they spit?
V-ing form
must I be spitting? must you be spitting? must she be spitting? must we be spitting? must you be spitting? must they be spitting?
Perfect
must I have spit? must you have spit? must she have spit? must we have spit? must you have spit? must they have spit?
V-ing perfect
must I have been spitting? must you have been spitting? must she have been spitting? must we have been spitting? must you have been spitting? must they have been spitting?
Interro-negative form
Simple form
must I not spit? must you not spit? must she not spit? must we not spit? must you not spit? must they not spit?
V-ing form
must I not be spitting? must you not be spitting? must she not be spitting? must we not be spitting? must you not be spitting? must they not be spitting?
Perfect
must I not have spit? must you not have spit? must she not have spit? must we not have spit? must you not have spit? must they not have spit?
V-ing perfect
must I not have been spitting? must you not have been spitting? must she not have been spitting? must we not have been spitting? must you not have been spitting? must they not have been spitting?