Translation:What were you doing that night in the tent?
Never heard of this rule, but I think it's nonsensical here anyway. "What were you doing in the tent that night" has a different meaning from " What were you doing that night in the tent?" To demonstrate that, consider this: "What were you doing in the tent that night? You should have been in the house."
Unfortunately some people whose native language is not English will tend to believe what you just wrote.
" What were you singing that night at the opera?" is perfectly fine, and so is the example given in this exercise. The word order can be varied depending on the desired emphasis.
Besides, we are learning Italian, not English.
'What were you doing in the tent that night?' was not accepted. Duolingo surely we are allowed to move the order of the words around to make it sound better in English? Yet I was marked wrong! Why??? Skimming through the comments, many others have asked the same question. Please amend! TIA :)
Unless you’re the police on official enquiries, why is that your business? Hmmm..?