Translation:Is the milk in the fridge?
Could it also mean "Is there milk in the fridge", or would that be different?
Yes but we need a more specific context. It could be short for *有*牛奶在冰箱里吗. This oral conciseness is not likely to be taught/tolerated in this course. Usually we should say 冰箱里有牛奶吗？.
Was your translation, "Milk at refrigerator inside?" because that's what I imagine with a word for word translation of this sentence. Regardless of what your translation was, you can't really translate word for word with Chinese and English.
My fists are starting to hurt from slamming my keyboard. I hate stuart little
No, because there is a 吗 at the end of the sentence, making it into a question
When I checked google translation, the correct translation is "Is there any milk in the fridge?" Boo, Dumb-Duo!
You musy not have used google translate very much for Chinese if you're calling it the correct translation. It uses a kind of AI algorithm to determine the translation, which isn't perfect.
BTW, I think your sentence would be more like 冰箱里有没有牛奶.
Because Google Translate is perfect and we should use it as a source for all translations... except that it is wrong a lot, especially with Chinese, so maybe blame Google Translate rather than Duo.
"is the milk inside the fridge?" It's not clear when words are meant to be used together like 's and here. Inside the fridge is more natural in English
Both "in" and "inside" the fridge are correct, clear and natural English depending somewhat on the speaker's region. In California I can say that "in" would be the norm, but I've been other places where "inside" would be common and even others where "ice box" would be used rather than "fridge".
Icebox isn't common but it was in my parents' generation. But "inside" the fridge is not common at all. Perhaps when you wanted to contrast strongly with outside the fridge.