I must sink you must sink he must sink we must sink you must sink they must sink
V-ing form
I must be sinking you must be sinking he must be sinking we must be sinking you must be sinking they must be sinking
Perfect
I must have sunk you must have sunk he must have sunk we must have sunk you must have sunk they must have sunk
V-ing perfect
I must have been sinking you must have been sinking he must have been sinking we must have been sinking you must have been sinking they must have been sinking
Negation
Simple form
I must not sink you must not sink he must not sink we must not sink you must not sink they must not sink
V-ing form
I must not be sinking you must not be sinking he must not be sinking we must not be sinking you must not be sinking they must not be sinking
Perfect
I must not have sunk you must not have sunk he must not have sunk we must not have sunk you must not have sunk they must not have sunk
V-ing perfect
I must not have been sinking you must not have been sinking he must not have been sinking we must not have been sinking you must not have been sinking they must not have been sinking
Interrogative form
Simple form
must I sink? must you sink? must he sink? must we sink? must you sink? must they sink?
V-ing form
must I be sinking? must you be sinking? must he be sinking? must we be sinking? must you be sinking? must they be sinking?
Perfect
must I have sunk? must you have sunk? must he have sunk? must we have sunk? must you have sunk? must they have sunk?
V-ing perfect
must I have been sinking? must you have been sinking? must he have been sinking? must we have been sinking? must you have been sinking? must they have been sinking?
Interro-negative form
Simple form
must I not sink? must you not sink? must he not sink? must we not sink? must you not sink? must they not sink?
V-ing form
must I not be sinking? must you not be sinking? must he not be sinking? must we not be sinking? must you not be sinking? must they not be sinking?
Perfect
must I not have sunk? must you not have sunk? must he not have sunk? must we not have sunk? must you not have sunk? must they not have sunk?
V-ing perfect
must I not have been sinking? must you not have been sinking? must he not have been sinking? must we not have been sinking? must you not have been sinking? must they not have been sinking?