
Verbo regular: snow - snowed - snowed
Forma simple | Forma con V-ing | 
| - - it could snow - - -  | - - it could be snowing - - -  | 
Perfecto | Perfecto con V-ing | 
| - - it could have snowed - - -  | - - it could have been snowing - - -  | 
Forma simple | Forma con V-ing | 
| - - it could not snow - - -  | - - it could not be snowing - - -  | 
Perfecto | Perfecto con V-ing | 
| - - it could not have snowed - - -  | - - it could not have been snowing - - -  | 
Forma simple | Forma con V-ing | 
| - - could it snow? - - -  | - - could it be snowing? - - -  | 
Perfecto | Perfecto con V-ing | 
| - - could it have snowed? - - -  | - - could it have been snowing? - - -  | 
Forma simple | Forma con V-ing | 
| - - could it not snow? - - -  | - - could it not be snowing? - - -  | 
Perfecto | Perfecto con V-ing | 
| - - could it not have snowed? - - -  | - - could it not have been snowing? - - -  |