The tress in this XYZ town have likely suffered from a hard winter.

You could use "the" in both places here, but one other thing "the" is used for is continuation. So if you start another sentence after this you would be referring to whatever "the" is pointing to.

The tress in this XYZ town have likely suffered from a hard winter. Their bark has disintegrated. (referring to the trees)
Tress in this XYZ town have likely suffered from the hard winter. It was colder than usual. (referring to the winter)
The tress in this XYZ town have likely suffered from the hard winter. (making one of the above comments here may be ambiguous, because you have not declared a single main subject)

Wow, thank you so much!

What's the difference between:

or
?
What's better?

The first is incorrect. Also, it should be "children" (since that is the plural of "child").

Edit: I hope there's also more to that sentence that you just haven't shown. If not, putting a full stop at the end of it makes no sense.

good = bon
well = bien

Hi, could somebody tell me what "ain't" mean?? I've met with that in book which i'm reading and i can't find what it means

That is a slang word for "isn't".

I saw the topic and i had to respond,since im swedish and even if we speak good english in general i often have too google spelling and just wanted to say thanks for thinking about us!!!

So, what, I do too. Don't think everyone knows how to spell, even if we can speak well. English spelling really makes very little sense, and has few rules and many exceptions ... I wish they would change it, but I doubt they will. There was supposedly a bill that almost passed to make words be spelled as you hear them ... but it didn't pass.

Shall we write:

or
?
shall we repeat "the" always? Is it necessary?

Unless you are talking about a particular phone, we would normally sayIf you had said then we could say "the great camera".

Yeah, adding "the" refers to a specific object, while "a/an" is any one of that object.

If someone had pointed out a specific camera and phone earlier, then you can use "the" to refer to these specifically. If they just bought any camera or any phone, you should use "a/an" because you have no clue exactly which camera or phone they bought.

Example:

Eariler:
A - Hey take a look at this new Nikon camera, it looks great, maybe I'll buy it.
B - If you want it, buy it.
A - I'll think about it.

Later:
B - So did you buy a camera ?

A:

Yeah, I bought the camera. (new Nikon)
Yeah, I bought a camera. (could be any camera)

Ok, since I started posting here, I haven't used "whom" once, and you are all probably shaking your fists at your monitors in anger. (Since we are (supposedly) nerds, I get this vision of Ross (Friends), correcting who/whom errors, in my head :P).

I came to think of it (again) as I was writing my last post:
<snip>..according to Hadiths, someone who get killed when...<snip>

I wasn't sure, and didn't want to look silly for trying to be sophisticated, so I played safe with "who", just like many native English speakers do, hehe..

I think whom is used when I'm referring to my self.
I.e. I recently had a vacation at my parents, whom I lived with the first 18 years of my life with.
and
I have to work more then I want to, because my boss, who is a jerk, won't employ a new guy.

Is this correct?

No, "who" is used when it acts as the subject of the subclause.

For example: "My boss, who is a jerk..."
What does "who" refer to? "My boss". If we replace "who" with its antecedent (= the word it refers to) we get:
"My boss is a jerk"
The subject of this sentence is "my boss" so we use "who".

Other example:
"My parents, whom I lived with the first 18 years of my life, ..."
What does "whom" refer to? To "My parents". So we replace whom with "my parents" and we get:
"I lived with my parents ..."
Here the subject of the sentence is not "my parents" but "I" so we use "whom".

It's ok to never use whom, but you should know that when you listen to it, 'who' sounds out of place when used instead of 'whom'.