I must cross you must cross he must cross we must cross you must cross they must cross
V-ing form
I must be crossing you must be crossing he must be crossing we must be crossing you must be crossing they must be crossing
Perfect
I must have crossed you must have crossed he must have crossed we must have crossed you must have crossed they must have crossed
V-ing perfect
I must have been crossing you must have been crossing he must have been crossing we must have been crossing you must have been crossing they must have been crossing
Negation
Simple form
I must not cross you must not cross he must not cross we must not cross you must not cross they must not cross
V-ing form
I must not be crossing you must not be crossing he must not be crossing we must not be crossing you must not be crossing they must not be crossing
Perfect
I must not have crossed you must not have crossed he must not have crossed we must not have crossed you must not have crossed they must not have crossed
V-ing perfect
I must not have been crossing you must not have been crossing he must not have been crossing we must not have been crossing you must not have been crossing they must not have been crossing
Interrogative form
Simple form
must I cross? must you cross? must he cross? must we cross? must you cross? must they cross?
V-ing form
must I be crossing? must you be crossing? must he be crossing? must we be crossing? must you be crossing? must they be crossing?
Perfect
must I have crossed? must you have crossed? must he have crossed? must we have crossed? must you have crossed? must they have crossed?
V-ing perfect
must I have been crossing? must you have been crossing? must he have been crossing? must we have been crossing? must you have been crossing? must they have been crossing?
Interro-negative form
Simple form
must I not cross? must you not cross? must he not cross? must we not cross? must you not cross? must they not cross?
V-ing form
must I not be crossing? must you not be crossing? must he not be crossing? must we not be crossing? must you not be crossing? must they not be crossing?
Perfect
must I not have crossed? must you not have crossed? must he not have crossed? must we not have crossed? must you not have crossed? must they not have crossed?
V-ing perfect
must I not have been crossing? must you not have been crossing? must he not have been crossing? must we not have been crossing? must you not have been crossing? must they not have been crossing?