Question 1

Why is no placed before mentirnos and not before prometió?

Accepted Answer

In Spanish, to say “promised not to do something,” the negation goes directly before the infinitive.  
- Prometió no mentirnos otra vez = “He promised not to lie to us again.”  
If you put no before prometió (as in Mi hermano no prometió mentirnos otra vez), it means “my brother didn’t promise to lie to us again,” i.e. he made no promise at all.

Question 2

Why is the pronoun nos attached to the end of mentir?

Accepted Answer

Spanish allows object pronouns to attach to infinitives. You have two options:  
1. Attach to the infinitive:  
   - Mi hermano prometió no mentirnos otra vez.  
2. Place before the conjugated verb:  
   - Mi hermano nos prometió no mentir otra vez.  
Both are correct, but attaching to the infinitive (mentirnos) is very common.

Question 3

Why is prometió in the preterite rather than the imperfect?

Accepted Answer

- The preterite (prometió) describes a completed action or promise made at a specific point in the past.  
- The imperfect (prometía) would imply an ongoing or habitual action in the past, which doesn’t fit here since it’s clearly one single promise.

Question 4

What does mentirnos mean exactly?

Accepted Answer

Mentir = “to lie”  
nos = indirect object pronoun for “us”  
So mentirnos literally means “to lie to us.”

Question 5

Is nos here a direct or indirect object pronoun?

Accepted Answer

It’s an indirect object pronoun because mentir takes an indirect object (you lie to someone).

Question 6

Could we use volver a instead of otra vez?

Accepted Answer

Yes. You can say:  
- Mi hermano prometió no volver a mentirnos.  
This structure (volver a + infinitive) also expresses “to do something again.”

Question 7

What’s the difference between otra vez and de nuevo?

Accepted Answer

Both mean “again.”  
- Otra vez is very common in everyday speech.  
- De nuevo is a bit more formal or typical in writing.  
You can usually swap them without changing the meaning.

Question 8

Could we rephrase it with a subordinate clause and a different tense?

Accepted Answer

Yes. A common alternative is:  
- Mi hermano prometió que no nos mentiría otra vez.  
Here you use a subordinate clause with the conditional (mentiría) to express a future action relative to the past (“future-in-the-past”).

Mi hermano prometió no mentirnos otra vez.

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