| singular | plural |
| Infinitive | | |
| alter | |
| present simple | | |
| 1 | I alter | we alter |
| 2 | you alter | you alter |
| 3 | he/she/it alters | they alter |
| past simple | | |
| 1 | I altered | we altered |
| 2 | you altered | you altered |
| 3 | he/she/it altered | they altered |
| future simple | | |
| 1 | I will/shall alter | we will/shall alter |
| 2 | you will/shall alter | you will/shall alter |
| 3 | he/she/it will/shall alter | they will/shall alter |
| conditional simple | | |
| 1 | I would alter | we would alter |
| 2 | you would alter | you would alter |
| 3 | he/she/it would alter | they would alter |
| present continuous | | |
| 1 | I am altering | we are altering |
| 2 | you are altering | you are altering |
| 3 | he/she/it is altering | they are altering |
| past continuous | | |
| 1 | I was altering | we were altering |
| 2 | you were altering | you were altering |
| 3 | he/she/it was altering | they were altering |
| future continuous | | |
| 1 | I will be altering | we will be altering |
| 2 | you will be altering | you will be altering |
| 3 | he/she/it will be altering | they will be altering |
| conditional continuous | | |
| 1 | I would be altering | we would be altering |
| 2 | you would be altering | you would be altering |
| 3 | he/she/it would be altering | they would be altering |
| present perfect | | |
| 1 | I have altered | we have altered |
| 2 | you have altered | you have altered |
| 3 | he/she/it has altered | they have altered |
| past perfect | | |
| 1 | I had altered | we had altered |
| 2 | you had altered | you had altered |
| 3 | he/she/it had altered | they had altered |
| future perfect | | |
| 1 | I will have altered | we will have altered |
| 2 | you will have altered | you will have altered |
| 3 | he/she/it will have altered | they will have altered |
| conditional perfect | | |
| 1 | I would have altered | we would have altered |
| 2 | you would have altered | you would have altered |
| 3 | he/she/it would have altered | they would have altered |
