Here are some pairs of sentences. I don't know the difference in meaning between each sentence in each pair.
How many apples did you eat?
How many apples have you eaten?
How many bags did you use?
How many bags have you used?
1. What is the difference in meaning between the two constructions?
2. Grammatically, what is the structure of "How many bags have you used"?
For example, for "how many bags have you used?", I notice that "used" is a past participle, but I'm still not sure how I might construct this sentence. I suspect my knowledge of grammar is lacking.
Here is one attempt:
"[You] [used] [five bags]" -- simple subject-verb-object sentence that uses very simple grammar that most beginners learn.
"How many bags did you use?" -- constructing a question, that can be answered with the previous sentence, by using "how many" at the beginning and doing an inversion of the [subject + verb] and [object]
"How many bags have you used?" -- ???? No idea how to construct this sentence! Does it have something to do with the passive voice? Where did the word "have" come from?