I must knuckle you must knuckle he must knuckle we must knuckle you must knuckle they must knuckle
V-ing form
I must be knuckling you must be knuckling he must be knuckling we must be knuckling you must be knuckling they must be knuckling
Perfect
I must have knuckled you must have knuckled he must have knuckled we must have knuckled you must have knuckled they must have knuckled
V-ing perfect
I must have been knuckling you must have been knuckling he must have been knuckling we must have been knuckling you must have been knuckling they must have been knuckling
Negation
Simple form
I must not knuckle you must not knuckle he must not knuckle we must not knuckle you must not knuckle they must not knuckle
V-ing form
I must not be knuckling you must not be knuckling he must not be knuckling we must not be knuckling you must not be knuckling they must not be knuckling
Perfect
I must not have knuckled you must not have knuckled he must not have knuckled we must not have knuckled you must not have knuckled they must not have knuckled
V-ing perfect
I must not have been knuckling you must not have been knuckling he must not have been knuckling we must not have been knuckling you must not have been knuckling they must not have been knuckling
Interrogative form
Simple form
must I knuckle? must you knuckle? must he knuckle? must we knuckle? must you knuckle? must they knuckle?
V-ing form
must I be knuckling? must you be knuckling? must he be knuckling? must we be knuckling? must you be knuckling? must they be knuckling?
Perfect
must I have knuckled? must you have knuckled? must he have knuckled? must we have knuckled? must you have knuckled? must they have knuckled?
V-ing perfect
must I have been knuckling? must you have been knuckling? must he have been knuckling? must we have been knuckling? must you have been knuckling? must they have been knuckling?
Interro-negative form
Simple form
must I not knuckle? must you not knuckle? must he not knuckle? must we not knuckle? must you not knuckle? must they not knuckle?
V-ing form
must I not be knuckling? must you not be knuckling? must he not be knuckling? must we not be knuckling? must you not be knuckling? must they not be knuckling?
Perfect
must I not have knuckled? must you not have knuckled? must he not have knuckled? must we not have knuckled? must you not have knuckled? must they not have knuckled?
V-ing perfect
must I not have been knuckling? must you not have been knuckling? must he not have been knuckling? must we not have been knuckling? must you not have been knuckling? must they not have been knuckling?