
Regular verb: attain - attained - attained
Simple form | V-ing form | 
| I must attain you must attain she must attain we must attain you must attain they must attain  | I must be attaining you must be attaining she must be attaining we must be attaining you must be attaining they must be attaining  | 
Perfect | V-ing perfect | 
| I must have attained you must have attained she must have attained we must have attained you must have attained they must have attained  | I must have been attaining you must have been attaining she must have been attaining we must have been attaining you must have been attaining they must have been attaining  | 
Simple form | V-ing form | 
| I mustn't attain you mustn't attain she mustn't attain we mustn't attain you mustn't attain they mustn't attain  | I mustn't be attaining you mustn't be attaining she mustn't be attaining we mustn't be attaining you mustn't be attaining they mustn't be attaining  | 
Perfect | V-ing perfect | 
| I mustn't have attained you mustn't have attained she mustn't have attained we mustn't have attained you mustn't have attained they mustn't have attained  | I mustn't have been attaining you mustn't have been attaining she mustn't have been attaining we mustn't have been attaining you mustn't have been attaining they mustn't have been attaining  | 
Simple form | V-ing form | 
| must I attain? must you attain? must she attain? must we attain? must you attain? must they attain?  | must I be attaining? must you be attaining? must she be attaining? must we be attaining? must you be attaining? must they be attaining?  | 
Perfect | V-ing perfect | 
| must I have attained? must you have attained? must she have attained? must we have attained? must you have attained? must they have attained?  | must I have been attaining? must you have been attaining? must she have been attaining? must we have been attaining? must you have been attaining? must they have been attaining?  | 
Simple form | V-ing form | 
| mustn't I attain? mustn't you attain? mustn't she attain? mustn't we attain? mustn't you attain? mustn't they attain?  | mustn't I be attaining? mustn't you be attaining? mustn't she be attaining? mustn't we be attaining? mustn't you be attaining? mustn't they be attaining?  | 
Perfect | V-ing perfect | 
| mustn't I have attained? mustn't you have attained? mustn't she have attained? mustn't we have attained? mustn't you have attained? mustn't they have attained?  | mustn't I have been attaining? mustn't you have been attaining? mustn't she have been attaining? mustn't we have been attaining? mustn't you have been attaining? mustn't they have been attaining?  |