| Present "alter" | I | alter | |
| Present Continuous "alter" | I | am altering | |
| Simple past "alter" | I | altered | |
| Past Continuous "alter" | I | was altering | |
| Present perfect "alter" | I | have altered | |
| Present perfect continuous "alter" | I | have been altering | |
| Past perfect "alter" | I | had altered | |
| Past perfect continuous "alter" | I | had been altering | |
| Future "alter" | I | will alter | |
| Future continuous "alter" | I | will be altering | |
| Future perfect "alter" | I | will have altered | |
| Future perfect continuous "alter" | I | will have been altering |