I must decrease you must decrease he must decrease we must decrease you must decrease they must decrease
V-ing form
I must be decreasing you must be decreasing he must be decreasing we must be decreasing you must be decreasing they must be decreasing
Perfect
I must have decreased you must have decreased he must have decreased we must have decreased you must have decreased they must have decreased
V-ing perfect
I must have been decreasing you must have been decreasing he must have been decreasing we must have been decreasing you must have been decreasing they must have been decreasing
Negation
Simple form
I must not decrease you must not decrease he must not decrease we must not decrease you must not decrease they must not decrease
V-ing form
I must not be decreasing you must not be decreasing he must not be decreasing we must not be decreasing you must not be decreasing they must not be decreasing
Perfect
I must not have decreased you must not have decreased he must not have decreased we must not have decreased you must not have decreased they must not have decreased
V-ing perfect
I must not have been decreasing you must not have been decreasing he must not have been decreasing we must not have been decreasing you must not have been decreasing they must not have been decreasing
Interrogative form
Simple form
must I decrease? must you decrease? must he decrease? must we decrease? must you decrease? must they decrease?
V-ing form
must I be decreasing? must you be decreasing? must he be decreasing? must we be decreasing? must you be decreasing? must they be decreasing?
Perfect
must I have decreased? must you have decreased? must he have decreased? must we have decreased? must you have decreased? must they have decreased?
V-ing perfect
must I have been decreasing? must you have been decreasing? must he have been decreasing? must we have been decreasing? must you have been decreasing? must they have been decreasing?
Interro-negative form
Simple form
must I not decrease? must you not decrease? must he not decrease? must we not decrease? must you not decrease? must they not decrease?
V-ing form
must I not be decreasing? must you not be decreasing? must he not be decreasing? must we not be decreasing? must you not be decreasing? must they not be decreasing?
Perfect
must I not have decreased? must you not have decreased? must he not have decreased? must we not have decreased? must you not have decreased? must they not have decreased?
V-ing perfect
must I not have been decreasing? must you not have been decreasing? must he not have been decreasing? must we not have been decreasing? must you not have been decreasing? must they not have been decreasing?