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