I must stretch you must stretch she must stretch we must stretch you must stretch they must stretch
V-ing form
I must be stretching you must be stretching she must be stretching we must be stretching you must be stretching they must be stretching
Perfect
I must have stretched you must have stretched she must have stretched we must have stretched you must have stretched they must have stretched
V-ing perfect
I must have been stretching you must have been stretching she must have been stretching we must have been stretching you must have been stretching they must have been stretching
Negation
Simple form
I mustn't stretch you mustn't stretch she mustn't stretch we mustn't stretch you mustn't stretch they mustn't stretch
V-ing form
I mustn't be stretching you mustn't be stretching she mustn't be stretching we mustn't be stretching you mustn't be stretching they mustn't be stretching
Perfect
I mustn't have stretched you mustn't have stretched she mustn't have stretched we mustn't have stretched you mustn't have stretched they mustn't have stretched
V-ing perfect
I mustn't have been stretching you mustn't have been stretching she mustn't have been stretching we mustn't have been stretching you mustn't have been stretching they mustn't have been stretching
Interrogative form
Simple form
must I stretch? must you stretch? must she stretch? must we stretch? must you stretch? must they stretch?
V-ing form
must I be stretching? must you be stretching? must she be stretching? must we be stretching? must you be stretching? must they be stretching?
Perfect
must I have stretched? must you have stretched? must she have stretched? must we have stretched? must you have stretched? must they have stretched?
V-ing perfect
must I have been stretching? must you have been stretching? must she have been stretching? must we have been stretching? must you have been stretching? must they have been stretching?
Interro-negative form
Simple form
mustn't I stretch? mustn't you stretch? mustn't she stretch? mustn't we stretch? mustn't you stretch? mustn't they stretch?
V-ing form
mustn't I be stretching? mustn't you be stretching? mustn't she be stretching? mustn't we be stretching? mustn't you be stretching? mustn't they be stretching?
Perfect
mustn't I have stretched? mustn't you have stretched? mustn't she have stretched? mustn't we have stretched? mustn't you have stretched? mustn't they have stretched?
V-ing perfect
mustn't I have been stretching? mustn't you have been stretching? mustn't she have been stretching? mustn't we have been stretching? mustn't you have been stretching? mustn't they have been stretching?