I must observe you must observe he must observe we must observe you must observe they must observe
Forma con V-ing
I must be observing you must be observing he must be observing we must be observing you must be observing they must be observing
Perfecto
I must have observed you must have observed he must have observed we must have observed you must have observed they must have observed
Perfecto con V-ing
I must have been observing you must have been observing he must have been observing we must have been observing you must have been observing they must have been observing
Negación
Forma simple
I must not observe you must not observe he must not observe we must not observe you must not observe they must not observe
Forma con V-ing
I must not be observing you must not be observing he must not be observing we must not be observing you must not be observing they must not be observing
Perfecto
I must not have observed you must not have observed he must not have observed we must not have observed you must not have observed they must not have observed
Perfecto con V-ing
I must not have been observing you must not have been observing he must not have been observing we must not have been observing you must not have been observing they must not have been observing
Forma interrogativa
Forma simple
must I observe? must you observe? must he observe? must we observe? must you observe? must they observe?
Forma con V-ing
must I be observing? must you be observing? must he be observing? must we be observing? must you be observing? must they be observing?
Perfecto
must I have observed? must you have observed? must he have observed? must we have observed? must you have observed? must they have observed?
Perfecto con V-ing
must I have been observing? must you have been observing? must he have been observing? must we have been observing? must you have been observing? must they have been observing?
Forma interro-negativa
Forma simple
must I not observe? must you not observe? must he not observe? must we not observe? must you not observe? must they not observe?
Forma con V-ing
must I not be observing? must you not be observing? must he not be observing? must we not be observing? must you not be observing? must they not be observing?
Perfecto
must I not have observed? must you not have observed? must he not have observed? must we not have observed? must you not have observed? must they not have observed?
Perfecto con V-ing
must I not have been observing? must you not have been observing? must he not have been observing? must we not have been observing? must you not have been observing? must they not have been observing?