I must strain you must strain he must strain we must strain you must strain they must strain
V-ing form
I must be straining you must be straining he must be straining we must be straining you must be straining they must be straining
Perfect
I must have strained you must have strained he must have strained we must have strained you must have strained they must have strained
V-ing perfect
I must have been straining you must have been straining he must have been straining we must have been straining you must have been straining they must have been straining
Negation
Simple form
I must not strain you must not strain he must not strain we must not strain you must not strain they must not strain
V-ing form
I must not be straining you must not be straining he must not be straining we must not be straining you must not be straining they must not be straining
Perfect
I must not have strained you must not have strained he must not have strained we must not have strained you must not have strained they must not have strained
V-ing perfect
I must not have been straining you must not have been straining he must not have been straining we must not have been straining you must not have been straining they must not have been straining
Interrogative form
Simple form
must I strain? must you strain? must he strain? must we strain? must you strain? must they strain?
V-ing form
must I be straining? must you be straining? must he be straining? must we be straining? must you be straining? must they be straining?
Perfect
must I have strained? must you have strained? must he have strained? must we have strained? must you have strained? must they have strained?
V-ing perfect
must I have been straining? must you have been straining? must he have been straining? must we have been straining? must you have been straining? must they have been straining?
Interro-negative form
Simple form
must I not strain? must you not strain? must he not strain? must we not strain? must you not strain? must they not strain?
V-ing form
must I not be straining? must you not be straining? must he not be straining? must we not be straining? must you not be straining? must they not be straining?
Perfect
must I not have strained? must you not have strained? must he not have strained? must we not have strained? must you not have strained? must they not have strained?
V-ing perfect
must I not have been straining? must you not have been straining? must he not have been straining? must we not have been straining? must you not have been straining? must they not have been straining?