I must cross you must cross she must cross we must cross you must cross they must cross
V-ing form
I must be crossing you must be crossing she must be crossing we must be crossing you must be crossing they must be crossing
Perfect
I must have crossed you must have crossed she 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 she must have been crossing we must have been crossing you must have been crossing they must have been crossing
Negation
Simple form
I mustn't cross you mustn't cross she mustn't cross we mustn't cross you mustn't cross they mustn't cross
V-ing form
I mustn't be crossing you mustn't be crossing she mustn't be crossing we mustn't be crossing you mustn't be crossing they mustn't be crossing
Perfect
I mustn't have crossed you mustn't have crossed she mustn't have crossed we mustn't have crossed you mustn't have crossed they mustn't have crossed
V-ing perfect
I mustn't have been crossing you mustn't have been crossing she mustn't have been crossing we mustn't have been crossing you mustn't have been crossing they mustn't have been crossing
Interrogative form
Simple form
must I cross? must you cross? must she cross? must we cross? must you cross? must they cross?
V-ing form
must I be crossing? must you be crossing? must she be crossing? must we be crossing? must you be crossing? must they be crossing?
Perfect
must I have crossed? must you have crossed? must she 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 she have been crossing? must we have been crossing? must you have been crossing? must they have been crossing?
Interro-negative form
Simple form
mustn't I cross? mustn't you cross? mustn't she cross? mustn't we cross? mustn't you cross? mustn't they cross?
V-ing form
mustn't I be crossing? mustn't you be crossing? mustn't she be crossing? mustn't we be crossing? mustn't you be crossing? mustn't they be crossing?
Perfect
mustn't I have crossed? mustn't you have crossed? mustn't she have crossed? mustn't we have crossed? mustn't you have crossed? mustn't they have crossed?
V-ing perfect
mustn't I have been crossing? mustn't you have been crossing? mustn't she have been crossing? mustn't we have been crossing? mustn't you have been crossing? mustn't they have been crossing?