Grammar check

[Luca]

I'll answer very quickly.

one day: it's equal? Usually not. To express more than one day (off) we use the numbers (two days off, three days off...) but for just one I would prefer the way I've always used. Obviously I think you know what it means (not "a day out"... but "a day home").

I'll pay you a hundred for a week. Wrong. I know in Italian we are used to saying like this, but in English you must compulsorily use that word in that way. An option could be: per week.

Is "time" not a abstract noun? Why insert "the" in this? What does the abstract noun have to do with the use of the? Look at the Italian translation. Do you say dimmi ora or dimmi l'ora?

_ darkness doesn't worry _ cats; _ cats can see in _ dark
Here I confess, I don't understand your book's rule. Maybe it's right, but I would rephrase it with:
when your're speaking about general objects, things, people or animals you needn't put an article. When you are speaking about a precise, punctual object, thing, person or animal you must use the article. So let's re-watch the sentence:

darkness(in general, not a specific one) doesn't worry _ cats (cats in general, not your cat, for example); _ cats (same) can see in (here the same, even if you can see some speakers that put an article and in this case it is not completely wrong) dark.

I'll give you some extra examples.

Why don't you call the postman who came here yesterday? = that one, that precise one.

Postmen use to get around with their motorcycles. = postmen in general, not a precise one.

[gio73]

I agree with Luca. In my book too it is explained how "the" is used. (I'm not quite sure that my precedent sentence is correct...)

Husbands are boring
The my friends' husbands are boring

[Luca]

I agree with Luca. In my book too it is explained how "the" is used, too(even though I would have used "also" or "even". (I'm not quite sure that if my precedent sentence is correct...)

$uarr $ $uarr $ $uarr $ $uarr $

[hamming_burst]

It's clear. Tanks Luca (and giò!).

Tomorrow another exercises

[Zero87]

Thanks to gio73 because I made a read error ("quite" instead of "quiet": I read "be quiet").

[gio73]

Hi zero

sta zitto is "be quiet!", like Marco said some posts ago.

[hamming_burst]

other easy exercises:

But _ interference with _ nature often brings _ disaster _ tree-felling sometimes _ fertile land into a dustbowl.

it's correct this phrase?

There'll always be a conflict between the old and the young.

the old and the young: are optional "the", confirm this?

_ power tends to corrupt and the absolute power corrupts absolutely.

absoulte power is a particular type of power then "the" is correct for me (the + adjective + noun), but it isn't. why?

[gio73]

There'll always be a conflict between the old and the young.

the old and the young: are optional "the", confirm this??

I think "the" is necessary, because the adjectives become nouns, but I'm learning like you, so my opinion is humblest (or most humble?) in all cases poorest is right.

_ power tends to corrupt and the absolute power corrupts absolutely.

absoulte power is a particular type of power then "the" is correct for me (the + adjective + noun), but it isn't. why?

But there are several cases of obsolute power: North Corea, Iran... now; in last century: U.R.S.S., fascism in Italy and other contries in Europe and South America..; more time ago... how many examples does it need?

[Luca]

the old and the young: are optional "the", confirm this?

I think "the" is necessary

Me too, I think it's optional. Indeed, I would have omitted the article. Gio, what you say is right, but despite this I have more frequently heard people not using the article in this case. To be more precise, it depends if you refer to one person or in general.
I meant you wanted to write old and young people, otherwise it seems like "il vecchio e il giovane"; if it was like this I would agree with Gio73.

o my opinion is humblest (or most humble?)

In which sense is "humble"? Do you know the meaning? Anyway if you want to use the superlative you should put the article before!

absoulte power is a particular type of power then "the" is correct for me (the + adjective + noun), but it isn't. why?

In this sentence, "power" has the same role of "absolute power", and even if you are confused because of some nuances, remember that you are speaking about general topics, general powers, not specif ones, like "the power of the Second World War" or "the power of Hitler" (even if it's better to use the saxon genitive).

If you want I can post some sentences in which you can clearly identify the right solution, just let me know.
In any case the rules you've studied are suitable at 90%.

[hamming_burst]

But there are several cases of obsolute power: North Corea, Iran... now; in last century: U.R.S.S., fascism in Italy and other contries in Europe and South America..; more time ago... how many examples does it need?

I haven't read that phrase in semantic way, but syntactically.

even if you are confused because of some nuances, remember that you are speaking about general topics, general powers, not specif ones

you're right...

If you want I can post some sentences in which you can clearly identify the right solution, just let me know.

ok, I'll write you if it needed/necessary. (it's correct?: te lo scriverò se necessario/sarà necessario )

He switched on the torch, read the meter and wrote the reading down on the back an envelope

What is the correct translation?
Accese la torcia, lesse il contatore e scrisse la lettura orizzontale sul retro di una busta

He said that he had had a book but that it hat been burnt in the fire in the Mr Smith's house.

Mr Smith's house = house of Mr Smith -> noun of noun.
My grammar report "the noun of noun" then "the" should be corrected in this case...because is a specific house (in your previous example: the power of Napoleone)