Present
| I | slacken |
| You | slacken |
| She | slackens |
| We | slacken |
| They | slacken |
Past
| I | slackened |
| You | slackened |
| She | slackened |
| We | slackened |
| They | slackened |
Perfect
| I | have | slackened |
| You | have | slackened |
| She | has | slackened |
| We | have | slackened |
| They | have | slackened |
Future
| I | will | slacken |
| You | will | slacken |
| She | will | slacken |
| We | will | slacken |
| They | will | slacken |
Past Perfect
| I | had | slackened |
| You | had | slackened |
| She | had | slackened |
| We | had | slackened |
| They | had | slackened |
Future Perfect
| I | will | have | slackened |
| You | will | have | slackened |
| She | will | have | slackened |
| We | will | have | slackened |
| They | will | have | slackened |
Present - Conditional
| I | would | slacken |
| You | would | slacken |
| She | would | slacken |
| We | would | slacken |
| They | would | slacken |
Perfect - Conditional
| I | would | have | slackened |
| You | would | have | slackened |
| She | would | have | slackened |
| We | would | have | slackened |
| They | would | have | slackened |