Learn Spanish (Latin America): El autobús embistió al tren; es más, rompió el parachoques. - The bus rammed the train; what's more, it broke the bumper.

This is the core of our current lesson! Normally, the personal a is only for people or pets. However, when both the subject and the object are inanimate (like a bus and a train), Spanish often uses an accusative a to mark the direct object. Here, al tren clearly shows that the train is the one receiving the impact, eliminating any ambiguity.

Could we leave the a out since the word order already shows the bus is the subject?

With verbs of physical impact or destruction (like embestir, golpear, or destruir), Spanish speakers almost always use the a when one inanimate object acts upon another. It instantly flags who hit whom, which is especially helpful because Spanish allows flexible word order. For example, you could say Al tren lo embistió el autobús and the meaning remains perfectly clear.

What is the infinitive of embistió, and why is it spelled with an i?

The infinitive is embestir (to ram or to charge). It is an -ir verb with an e to i stem change. As a quick refresher, remember that these stem-changing -ir verbs keep the vowel change in the third-person singular and plural of the preterite tense, which is why it becomes embistió.

How exactly does function in this sentence?