Final answer:
The correct Spanish equivalent is "Ellos se acuestan a las diez".
Step-by-step explanation:
The correct Spanish equivalent to the phrase "They go to bed at ten o'clock" is Ellos se acuestan a las diez.
The subject pronoun ellos is used to represent "they". The reflexive verb acostarse means "to go to bed". And the phrase a las diez indicates "at ten o'clock".
Therefore, the correct translation is "Ellos se acuestan a las diez".
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