"Strange! Why is there nobody home?"

Translation: 奇怪！为什么没有人在家？

[Elmurza0110]

Why is it incorrect to say: 为什么在家没有人?

[looli23]

Because then there would be two verbs in the main sentence “在” and“没有”. 在 in 在家 is a verb, and 在家 doesn't correlate to "at home" in English. We say 我在家, where 在 is a verb, but in English, the verb is "is": I [am] at home.
Correct sentence should be 为什么家里没有人。

[Levi]

You just lost me there, pal.

What then does 在家 correlate to in English, if not ‘at home’?

“ [...] where 在 is a verb, but in English, the verb is "is": ” - and when you conjugate “is” it becomes “am” = ‘I is at home’ becomes “I am at home”
2018.09.25