Help the unlucky driver finish his text message to his friend by choosing the correct verb for each blank.

Yesterday, my car broke down in the rain, so I had to walk three miles to work! At least I didn't have to pay for parking.

Yesterday, my car broke down in the rain, so I had to walk three miles to work!

Because this happened "yesterday," we need a past tense verb. The modal must does not have a past tense form, so we always use had to for obligations in the past.

At least I didn't have to pay for parking.

To express a lack of obligation in the past (something that wasn't necessary), we use didn't have to. "Must not" cannot be used for the past tense.