I must extend you must extend he must extend we must extend you must extend they must extend
V-ing form
I must be extending you must be extending he must be extending we must be extending you must be extending they must be extending
Perfect
I must have extended you must have extended he must have extended we must have extended you must have extended they must have extended
V-ing perfect
I must have been extending you must have been extending he must have been extending we must have been extending you must have been extending they must have been extending
Negation
Simple form
I must not extend you must not extend he must not extend we must not extend you must not extend they must not extend
V-ing form
I must not be extending you must not be extending he must not be extending we must not be extending you must not be extending they must not be extending
Perfect
I must not have extended you must not have extended he must not have extended we must not have extended you must not have extended they must not have extended
V-ing perfect
I must not have been extending you must not have been extending he must not have been extending we must not have been extending you must not have been extending they must not have been extending
Interrogative form
Simple form
must I extend? must you extend? must he extend? must we extend? must you extend? must they extend?
V-ing form
must I be extending? must you be extending? must he be extending? must we be extending? must you be extending? must they be extending?
Perfect
must I have extended? must you have extended? must he have extended? must we have extended? must you have extended? must they have extended?
V-ing perfect
must I have been extending? must you have been extending? must he have been extending? must we have been extending? must you have been extending? must they have been extending?
Interro-negative form
Simple form
must I not extend? must you not extend? must he not extend? must we not extend? must you not extend? must they not extend?
V-ing form
must I not be extending? must you not be extending? must he not be extending? must we not be extending? must you not be extending? must they not be extending?
Perfect
must I not have extended? must you not have extended? must he not have extended? must we not have extended? must you not have extended? must they not have extended?
V-ing perfect
must I not have been extending? must you not have been extending? must he not have been extending? must we not have been extending? must you not have been extending? must they not have been extending?