Conjugación del verbo inglés
CAN HAPPEN

Verbo regular: happen - happened - happened

Afirmación

Forma simple	Forma con V-ing
- - it can happen - - -	- - it can be happening - - -
Perfecto	Perfecto con V-ing
- - it can have happened - - -	- - it can have been happening - - -

Negación

Forma simple	Forma con V-ing
- - it can't happen - - -	- - it can't be happening - - -
Perfecto	Perfecto con V-ing
- - it can't have happened - - -	- - it can't have been happening - - -

Forma interrogativa

Forma simple	Forma con V-ing
- - can it happen? - - -	- - can it be happening? - - -
Perfecto	Perfecto con V-ing
- - can it have happened? - - -	- - can it have been happening? - - -

Forma interro-negativa

Forma simple	Forma con V-ing
- - can't it happen? - - -	- - can't it be happening? - - -
Perfecto	Perfecto con V-ing
- - can't it have happened? - - -	- - can't it have been happening? - - -