Final answer:
The sentence is grammatically correct; there are no errors in the numbered parts of the sentence.
Step-by-step explanation:
The sentence provided, "Shhh. Grandpa watches (1) the World Cup in (2) the living room. We don’t want (3) to disturb (4) him.", does not contain any grammatical errors. Each numbered part of the sentence uses correct verb tense, prepositions, and syntax appropriate for standard English. The verb 'watches' correctly aligns with the singular subject 'Grandpa', the phrase 'in the living room' appropriately describes the location, 'don’t want' correctly reflects the negative desire, and 'to disturb' is the correct infinitive form to express the intent not to interrupt Grandpa.