Because Carlos is a masculine name, I would use the word <em>el </em> to talk about him.
<h2>
Explanation:</h2>
The simple present tense is used to talk about habitual actions or routines. This tense is also used to describe things that happen now or in the near future. On the other hand, the preterite tense is one of two simple past tenses. It is used to describe actions that took place or were completed at a certain point in the past. So we need to change the simple present form of the verb dar for the first person singular, which is doy to the preterite form of this verb for the same person, which is dí. Finally:
<u>SIMPLE PRESENT:</u>
<em>Yo le </em><em>doy </em><em>un lápiz a mi amigo.</em>
<u>PRETERITE:</u>
<em>Yo le </em><em>dí </em><em>un lápiz a mi amigo.</em>
