must waterproof
Regular verb: waterproof - waterproofed- waterproofed

Affirmation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must waterproof
you must waterproof
he must waterproof
we must waterproof
you must waterproof
they must waterproof 	I must be waterproofing
you must be waterproofing
he must be waterproofing
we must be waterproofing
you must be waterproofing
they must be waterproofing	I must have waterproofed
you must have waterproofed
he must have waterproofed
we must have waterproofed
you must have waterproofed
they must have waterproofed	I must have been waterproofing
you must have been waterproofing
he must have been waterproofing
we must have been waterproofing
you must have been waterproofing
they must have been waterproofing	

Negation 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
I must not waterproof
you must not waterproof
he must not waterproof
we must not waterproof
you must not waterproof
they must not waterproof 	I must not be waterproofing
you must not be waterproofing
he must not be waterproofing
we must not be waterproofing
you must not be waterproofing
they must not be waterproofing	I must not have waterproofed
you must not have waterproofed
he must not have waterproofed
we must not have waterproofed
you must not have waterproofed
they must not have waterproofed	I must not have been waterproofing
you must not have been waterproofing
he must not have been waterproofing
we must not have been waterproofing
you must not have been waterproofing
they must not have been waterproofing	

Interrogative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I waterproof?
must you waterproof?
must he waterproof?
must we waterproof?
must you waterproof?
must they waterproof? 	must I be waterproofing?
must you be waterproofing?
must he be waterproofing?
must we be waterproofing?
must you be waterproofing?
must they be waterproofing? 	must I have waterproofed?
must you have waterproofed?
must he have waterproofed?
must we have waterproofed?
must you have waterproofed?
must they have waterproofed? 	must I have been waterproofing?
must you have been waterproofing?
must he have been waterproofing?
must we have been waterproofing?
must you have been waterproofing?
must they have been waterproofing? 	

Interro-negative form 	
Simple form 	V-ing form 	Perfect 	V-ing perfect 	
must I not waterproof?
must you not waterproof?
must he not waterproof?
must we not waterproof?
must you not waterproof?
must they not waterproof? 	must I not be waterproofing?
must you not be waterproofing?
must he not be waterproofing?
must we not be waterproofing?
must you not be waterproofing?
must they not be waterproofing? 	must I not have waterproofed?
must you not have waterproofed?
must he not have waterproofed?
must we not have waterproofed?
must you not have waterproofed?
must they not have waterproofed? 	must I not have been waterproofing?
must you not have been waterproofing?
must he not have been waterproofing?
must we not have been waterproofing?
must you not have been waterproofing?
must they not have been waterproofing?