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