I must spare you must spare he must spare we must spare you must spare they must spare
V-ing form
I must be sparing you must be sparing he must be sparing we must be sparing you must be sparing they must be sparing
Perfect
I must have spared you must have spared he must have spared we must have spared you must have spared they must have spared
V-ing perfect
I must have been sparing you must have been sparing he must have been sparing we must have been sparing you must have been sparing they must have been sparing
Negation
Simple form
I must not spare you must not spare he must not spare we must not spare you must not spare they must not spare
V-ing form
I must not be sparing you must not be sparing he must not be sparing we must not be sparing you must not be sparing they must not be sparing
Perfect
I must not have spared you must not have spared he must not have spared we must not have spared you must not have spared they must not have spared
V-ing perfect
I must not have been sparing you must not have been sparing he must not have been sparing we must not have been sparing you must not have been sparing they must not have been sparing
Interrogative form
Simple form
must I spare? must you spare? must he spare? must we spare? must you spare? must they spare?
V-ing form
must I be sparing? must you be sparing? must he be sparing? must we be sparing? must you be sparing? must they be sparing?
Perfect
must I have spared? must you have spared? must he have spared? must we have spared? must you have spared? must they have spared?
V-ing perfect
must I have been sparing? must you have been sparing? must he have been sparing? must we have been sparing? must you have been sparing? must they have been sparing?
Interro-negative form
Simple form
must I not spare? must you not spare? must he not spare? must we not spare? must you not spare? must they not spare?
V-ing form
must I not be sparing? must you not be sparing? must he not be sparing? must we not be sparing? must you not be sparing? must they not be sparing?
Perfect
must I not have spared? must you not have spared? must he not have spared? must we not have spared? must you not have spared? must they not have spared?
V-ing perfect
must I not have been sparing? must you not have been sparing? must he not have been sparing? must we not have been sparing? must you not have been sparing? must they not have been sparing?