Learn Spanish (Latin America): El cómplice le acababa de atar los cordones al compañero. - The accomplice had just tied the classmate's shoelaces.

The phrase acabar de followed by an infinitive means "to have just done something." To say someone had just done something before another past event, you must use the imperfect tense (acababa). If you used the preterite (acabó), it would sound more like "he finally finished tying" rather than "he had just tied."

Why does it say los cordones instead of sus cordones?

In Spanish, when talking about putting on, taking off, or adjusting clothing and body parts, you typically use definite articles (el, la, los, las) instead of possessive adjectives (su, sus). The ownership is instead shown by the indirect object pronoun le, meaning the action is done "to him."

Is it necessary to use both le and al compañero?

Yes, this is a standard rule in Spanish known as indirect object duplication. Even though al compañero explicitly tells us who receives the action, the indirect object pronoun le is almost always grammatically required alongside it to anchor the sentence.

How could we add "without the classmate noticing" to practice this lesson's focus on sin que clauses?