Translation:The watch is older than our house.
Either "clock" or "watch" can be used in this translation.
Now my question. Why did you decide that the word "clock" was the problem? Doesn't the sentence contain other words?
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From what I see what you wrote is fine and should have been accepted. If we had more information we might be able to help more, a screenshot would be good. Which word did they say was wrong, what did they show as the correct word. If there is an glitch we need to report it but we need more information.