
Verbo regular: rain - rained - rained
Forma simple | Forma con V-ing | 
| - - it must rain - - -  | - - it must be raining - - -  | 
Perfecto | Perfecto con V-ing | 
| - - it must have rained - - -  | - - it must have been raining - - -  | 
Forma simple | Forma con V-ing | 
| - - it mustn't rain - - -  | - - it mustn't be raining - - -  | 
Perfecto | Perfecto con V-ing | 
| - - it mustn't have rained - - -  | - - it mustn't have been raining - - -  | 
Forma simple | Forma con V-ing | 
| - - must it rain? - - -  | - - must it be raining? - - -  | 
Perfecto | Perfecto con V-ing | 
| - - must it have rained? - - -  | - - must it have been raining? - - -  | 
Forma simple | Forma con V-ing | 
| - - mustn't it rain? - - -  | - - mustn't it be raining? - - -  | 
Perfecto | Perfecto con V-ing | 
| - - mustn't it have rained? - - -  | - - mustn't it have been raining? - - -  |