Molto/ Tanto/ Parecchio
In the case of molto/ tanto, at least, they get used on Duolingo interchangeably. Is there a good reason to choose one over the other?
Parecchio has been used to mean “quite a lot/ rather a lot”, and that makes it an adjective since the word “of” is implied—I’ve never seen it used as an adverb, but can it be?
So then: Does the case ever arise where you would use the preposition “di” along with any of molto, tanto, or parecchio?
Allow me to demonstrate with an English example.
I eat a lot of pasta.
I eat pasta a lot.
These two sentences have different meanings because in the first one, “a lot (of)” is an adjective; referring to the pasta.
In the second one, “a lot” is an adverb, referring to “eating”.
How would you say the sentences above in Italian, and keep the English meaning? Can you just move the position of “molto” in the sentence, or would you ever add “di” to clarify?
Mangio molto pasta (or, is it molta? Or even molte? I’m never sure.)
Mangio molto di pasta
Mangio pasta molto
Mangio pasta parrechio
"Molto" is either an adjective or an adverb. So you cannot say " Mangio molto di pasta". Correct sentences would be "Mangio molta pasta" or "Mangio molto la pasta". In the former "molta" is an adjective, in the latter "molto" is an adverb.
So your second sentence (translated literally) is, "I eat (it) a lot, the pasta." Very interesting!
And it is molta pasta. Too strange! The rule must be to match gender and quantity if using molto as an adjective, but it remains molto-- no matter what-- if it is used as an adverb; correct?
Any thoughts on the difference between molto and tanto?
Well, the problem is more that word order in Italian may be different from English, so literal translations may result in "unnatural" sentences.
"Molto" and "tanto" are mostly interchangeable. "Tanto" is a little more emphatic, especially in spoken Italian. For example: "ho tanto freddo/sonno/caldo!", "Mi fa tanto male!" or "Ti voglio tanto bene!". Moreover "tanto" is used in the pattern "tanto... quanto" (as much as). You can also find "tanto" in spoken Italian with a meaning close to "in any case" to emphasise that the action done is useless. "Puoi dirgli quello che vuoi, tanto non ti ascolta!".
There are other different usages but in your sentences they have the same meaning.