must happen
Verbo regular: happen - happened- happened

Afirmação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
-
-
it must happen
-
-
- 	-
-
it must be happening
-
-
- 	-
-
it must have happened
-
-
- 	-
-
it must have been happening
-
-
- 	

Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
-
-
it must not happen
-
-
- 	-
-
it must not be happening
-
-
- 	-
-
it must not have happened
-
-
- 	-
-
it must not have been happening
-
-
- 	

Forma interrogativa 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
-
-
must it happen?
-
-
- 	-
-
must it be happening?
-
-
- 	-
-
must it have happened?
-
-
- 	-
-
must it have been happening?
-
-
- 	

Forma interro-Negação 	
Forma simple 	Forma com V-ing 	Perfeito 	Perfeito com V-ing 	
-
-
must it not happen?
-
-
- 	-
-
must it not be happening?
-
-
- 	-
-
must it not have happened?
-
-
- 	-
-
must it not have been happening?
-
-
-