I must trek you must trek he must trek we must trek you must trek they must trek
V-ing form
I must be trekking you must be trekking he must be trekking we must be trekking you must be trekking they must be trekking
Perfect
I must have trekked you must have trekked he 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 he must have been trekking we must have been trekking you must have been trekking they must have been trekking
Negation
Simple form
I must not trek you must not trek he must not trek we must not trek you must not trek they must not trek
V-ing form
I must not be trekking you must not be trekking he must not be trekking we must not be trekking you must not be trekking they must not be trekking
Perfect
I must not have trekked you must not have trekked he must not have trekked we must not have trekked you must not have trekked they must not have trekked
V-ing perfect
I must not have been trekking you must not have been trekking he must not have been trekking we must not have been trekking you must not have been trekking they must not have been trekking
Interrogative form
Simple form
must I trek? must you trek? must he trek? must we trek? must you trek? must they trek?
V-ing form
must I be trekking? must you be trekking? must he be trekking? must we be trekking? must you be trekking? must they be trekking?
Perfect
must I have trekked? must you have trekked? must he 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 he have been trekking? must we have been trekking? must you have been trekking? must they have been trekking?
Interro-negative form
Simple form
must I not trek? must you not trek? must he not trek? must we not trek? must you not trek? must they not trek?
V-ing form
must I not be trekking? must you not be trekking? must he not be trekking? must we not be trekking? must you not be trekking? must they not be trekking?
Perfect
must I not have trekked? must you not have trekked? must he not have trekked? must we not have trekked? must you not have trekked? must they not have trekked?
V-ing perfect
must I not have been trekking? must you not have been trekking? must he not have been trekking? must we not have been trekking? must you not have been trekking? must they not have been trekking?