| Present "firm" | I | firm | |
| Present Continuous "firm" | I | am firming | |
| Simple past "firm" | I | firmed | |
| Past Continuous "firm" | I | was firming | |
| Present perfect "firm" | I | have firmed | |
| Present perfect continuous "firm" | I | have been firming | |
| Past perfect "firm" | I | had firmed | |
| Past perfect continuous "firm" | I | had been firming | |
| Future "firm" | I | will firm | |
| Future continuous "firm" | I | will be firming | |
| Future perfect "firm" | I | will have firmed | |
| Future perfect continuous "firm" | I | will have been firming |