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