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