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