must perturb
Verbo regular: perturb - perturbed- perturbed

Afirmação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I must perturb
you must perturb
he must perturb
we must perturb
you must perturb
they must perturb 	I must be perturbing
you must be perturbing
he must be perturbing
we must be perturbing
you must be perturbing
they must be perturbing	I must have perturbed
you must have perturbed
he must have perturbed
we must have perturbed
you must have perturbed
they must have perturbed	I must have been perturbing
you must have been perturbing
he must have been perturbing
we must have been perturbing
you must have been perturbing
they must have been perturbing	

Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
I must not perturb
you must not perturb
he must not perturb
we must not perturb
you must not perturb
they must not perturb 	I must not be perturbing
you must not be perturbing
he must not be perturbing
we must not be perturbing
you must not be perturbing
they must not be perturbing	I must not have perturbed
you must not have perturbed
he must not have perturbed
we must not have perturbed
you must not have perturbed
they must not have perturbed	I must not have been perturbing
you must not have been perturbing
he must not have been perturbing
we must not have been perturbing
you must not have been perturbing
they must not have been perturbing	

Forma interrogativa 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
must I perturb?
must you perturb?
must he perturb?
must we perturb?
must you perturb?
must they perturb? 	must I be perturbing?
must you be perturbing?
must he be perturbing?
must we be perturbing?
must you be perturbing?
must they be perturbing? 	must I have perturbed?
must you have perturbed?
must he have perturbed?
must we have perturbed?
must you have perturbed?
must they have perturbed? 	must I have been perturbing?
must you have been perturbing?
must he have been perturbing?
must we have been perturbing?
must you have been perturbing?
must they have been perturbing? 	

Forma interro-Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
must I not perturb?
must you not perturb?
must he not perturb?
must we not perturb?
must you not perturb?
must they not perturb? 	must I not be perturbing?
must you not be perturbing?
must he not be perturbing?
must we not be perturbing?
must you not be perturbing?
must they not be perturbing? 	must I not have perturbed?
must you not have perturbed?
must he not have perturbed?
must we not have perturbed?
must you not have perturbed?
must they not have perturbed? 	must I not have been perturbing?
must you not have been perturbing?
must he not have been perturbing?
must we not have been perturbing?
must you not have been perturbing?
must they not have been perturbing?