In the given sentence "Rompí mi computadora portátil la semana pasada, así que necesito comprar una nueva," the preterite -er verb is "necesito."
Here's a breakdown to explain:
1. "Rompí" is a preterite -ir verb (from the verb "romper").
2. "Necesito" is a preterite -er verb (from the verb "necesitar").
3. In this sentence, "necesito" indicates the need to buy a new computer.
By identifying the preterite -er verb "necesito," we can see that the speaker expresses the necessity of purchasing a new computer due to breaking the old one.
