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