"The garlic is on the plate."
Translation:L'aglio è nel piatto.
let me take you back to the "mouse is in the book" I'm confused since they use nello, does that mean the mouse is a character in the book, the mouse is sitting on the book or indeed is the mouse crushed within the book. We should be told. I'm not sure now is the garlic sitting on the plate, in a stencil on the plate or indeed did some fool bake the garlic into the plate?
Seriously though, what are the rules about nel and nello?
Nel and nello are prepositions combined with the definite articles which stand before nouns. So "nel" is the result of combining the preposition IN+ IL piatto. IN mostly means literally "in something" and IL before a noun describes it as a masculine singular noun. So for a female singular noun it would be IN+LA=nella. There is also a masculine singular noun LO, as in lo zaino(a backpack) so IN+LO= nello. As for the use of prepositions such as IN, A, DI, DA etc there are various uses for each one and although there are rules, there are also many exemptions so don't try to rationalize TOO much and try to get them in your ear instead. Hope this helps
While "sul" certainly is a more literal translation of "on the" then "nel", this doesn't imply the corresponding idiom uses the preposition with the closest word-for-word translation. Prepositions are notorious for having quite different usage in idioms of different languages. That being said - my Italian is not good enough yet to be certain if we have an error here, so I tend to trust in the course creators, until somebody has a strong argument for the opposite (like quoting a good reference, info from a native speaker,...).