I must strive you must strive he must strive we must strive you must strive they must strive
V-ing form
I must be striving you must be striving he must be striving we must be striving you must be striving they must be striving
Perfect
I must have striven you must have striven he must have striven we must have striven you must have striven they must have striven
V-ing perfect
I must have been striving you must have been striving he must have been striving we must have been striving you must have been striving they must have been striving
Negation
Simple form
I mustn't strive you mustn't strive he mustn't strive we mustn't strive you mustn't strive they mustn't strive
V-ing form
I mustn't be striving you mustn't be striving he mustn't be striving we mustn't be striving you mustn't be striving they mustn't be striving
Perfect
I mustn't have striven you mustn't have striven he mustn't have striven we mustn't have striven you mustn't have striven they mustn't have striven
V-ing perfect
I mustn't have been striving you mustn't have been striving he mustn't have been striving we mustn't have been striving you mustn't have been striving they mustn't have been striving
Interrogative form
Simple form
must I strive? must you strive? must he strive? must we strive? must you strive? must they strive?
V-ing form
must I be striving? must you be striving? must he be striving? must we be striving? must you be striving? must they be striving?
Perfect
must I have striven? must you have striven? must he have striven? must we have striven? must you have striven? must they have striven?
V-ing perfect
must I have been striving? must you have been striving? must he have been striving? must we have been striving? must you have been striving? must they have been striving?
Interro-negative form
Simple form
mustn't I strive? mustn't you strive? mustn't he strive? mustn't we strive? mustn't you strive? mustn't they strive?
V-ing form
mustn't I be striving? mustn't you be striving? mustn't he be striving? mustn't we be striving? mustn't you be striving? mustn't they be striving?
Perfect
mustn't I have striven? mustn't you have striven? mustn't he have striven? mustn't we have striven? mustn't you have striven? mustn't they have striven?
V-ing perfect
mustn't I have been striving? mustn't you have been striving? mustn't he have been striving? mustn't we have been striving? mustn't you have been striving? mustn't they have been striving?