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