"It is a menu."
Translation:Det er en menu.
If an unspecified IT is the subject of the sentence-performing the action-it'll always be the default DET. "It is rainy," "It [I don't know what though] is smoking."
On the other hand, if I know what I'm talking about, I'll use the appropriate form. So for "The book is..." it'll be "Den [bogen] er...."
And of course when IT is an object ("She eats it") we'll use the form appropriate to the item
I notice that in the tips and notes it says that 'it' can be den or det. I had assumed that the choice would depend on the gender of the objects, but i must be wrong, as here we have 'en menu' and we're using 'det'. The same happen with 'en bog'. Can someone explain why/when we should use 'den/det' for it?
I think here it's because "it" at first isn't defined until you say that "it" is a menu or a book or a tree and so on. A sentence or clause after this might then go something like this Det er en menu og den er på dansk. meaning "It is a menu and it is in Danish" (not the best example, I know, but my brain isn't quite with it today).
Can someone explain to me how do i know when to use et and when to use en. For example: at barn, en sandwich. Thanks!
It is dependent on the gender. Et barn, en sandwich, et hus, en bog. There's no logic really to the gendering of words, you need to learn each individually :) rule of thumb is that if you forget the gender for the word, there are more 'en' words in Danish so better to go for 'en'!