Why do -car and -gar verbs in Spanish change spelling the first person of preterite?

You're right! The -car, -gar, and -zar verbs in Spanish do indeed change their spelling in the first person singular of the preterite tense (yo form). This change is due to a specific rule of Spanish grammar that dictates how these verbs conjugate.

Here's a breakdown of the changes and the reason behind them:

Why the changes?

The changes in the -car, -gar, and -zar verbs are due to a phenomenon known as stem changes in Spanish. This occurs because the verb stem, which is the base form of the verb before the ending is added, undergoes a modification depending on the conjugation.

How the Changes Work:

* -car verbs: The "c" changes to a "qu" in the first person singular of the preterite.

* Example: *cantar* (to sing) - *canté* (I sang)

* -gar verbs: The "g" changes to a "gu" in the first person singular of the preterite.

* Example: *pagar* (to pay) - *pagué* (I paid)

* -zar verbs: The "z" changes to a "c" in the first person singular of the preterite.

* Example: *empezar* (to start) - *empecé* (I started)

The Reason for Stem Changes:

The stem changes in these verbs are a result of the phonetic properties of Spanish. The "c," "g," and "z" sounds in these verbs are often pronounced differently depending on the following vowel. The changes in the preterite are a way to maintain a more consistent pronunciation.

For example:

* In *canté* (I sang), the "qu" is needed to keep the "c" sound hard before the "e" vowel, preventing it from being pronounced like the "s" sound in "sang."

* In *pagué* (I paid), the "gu" keeps the "g" sound hard before the "e," preventing it from becoming a soft "j" sound.

* In *empecé* (I started), the "c" before the "e" preserves the hard "c" sound, rather than becoming a "s" sound.

In essence, the spelling changes in the first person singular of the preterite for -car, -gar, and -zar verbs are a way to ensure consistent pronunciation and avoid potential misinterpretations.