Overall this doesn't sound too bad but you need to make a few corrections related to the usage of certain words / phrases.
1. Distinguish between "adolescence" and "adolescent(s)." When the latter is in plural form both of the words sound almost the same but have different meanings and different spellings. I believe you mixed those two up a few times.
2. "as well as" should not be split.
Examples:
Your sentence: ...increased conflicts AS WELL with themselves AS other people...
Should be: ...increased conflicts with themselves AS WELL AS (with) other people...
Your sentence: There is a lot of various AS WELL biological AS physical changes...
Should be: There is a lot of various biological AS WELL AS physical changes...
3. You seem to be overusing phrase “what is more.” I suggest replacing it with synonyms. (additionally, furthermore, moreover, besides that)
>These problems either are really very serious or seem to be so.
These problems are or at least seem to be very serious.
>Sometimes it is difficult for adults to understand negative behaviour
>typical at this age like: lack of truthfulness, of control, increased
>conflicts as well (with?) themselves as other people (particularly as
>parents and teachers).
…typical at this age such as: lack of truthfulness, lack of self-control, increased conflicts with themselves as well as other people (particularly parents and teachers).
>In my opinion the most puzzling situation is
>when adolescence try such dangerous sorts of rebel like drinking
>alcohol, drug, escape from home, sex.
…adolescenTS try such potentially dangerous forms of rebellion as alcohol, drugs, sex, or home escapes.
>What is more, most adults don't
>remember or don't want to remember how to axplain enormous (in their
>opinion) adolescence's behaviour.
Explain (not axplain);
Also, here is a perfect example where you should use adolescent (behavior) instead of adolescence.
Finally – what do you mean by “enormous” here? This word (meaning pretty much big / huge, etc.) doesn’t fit here, or at least I have no idea what you’re trying to say.
>There is a lot of various as well
>biological as physical changes in adolescence organism and young
>people can't manage these problems.
During the adolescence there are many biological as well as physical body changes and the young people do not seem to know how to manage them.
>Young people put question to themselves about sense of life, they have
>doubts of philosophy of life.
Young people ask themselves about the sense of life; they question established philosophies and standard ways of thinking.
>That is why young people experience uncertainty and loss or in most difficult
>situation even negation.
Not sure again what you are trying to say here…
Sometimes young person feels best when he is
>in a world of his own, he always feels alien, but in another
>przypadkach his behaviour is simply shocking he doesn't care what
>other people think of him.
Przypadkach = cases
And if it is plural (caseS) then it has to be preceded by other instead of another
>It seems, this difficut time lasts from 11 till 15 years old for girls
>and between 13 and 17 years old for boys.
It seems that this difficult period lasts between the ages of 11 and 15 for girls, and 13 and 17 for boys.
>They don't know why, in one
>time they feel happy and in another - sadness and lack of
>understanding seem to be the most important in their lives.
The adolescents do not know why one moment they feel happy and the next they are sad and nothing in life makes sense.
>You can mention three groups of feelings:
You can identify three groups of feelings:
>- aggressive states - young people are violent, they lose their temper
>quickly and provoke quarrels too often, sometimes they are very
>arogant,
Get rid of “states” (just aggressive)
Provoke quarrels = get into fights
arogant = arrogant
>- defensive states - they feel sadness, fear, rancour, angst,
Get rid of “states” (just defensive)
>- positive states - through the period of adolescence young people
>need love, sensitive, friendship and they are more emotional than they
>would like to be.
Get rid of “states” (just positive)
…need love, sensitivITY, friendship….
>Some time later, young people are in want of rules, value and sense of
>their own lives and instead of lack of compromise they try to tolerate
>and be liberal.
…young people want rules, values and deeper meaning of their own lives. They replace the inability to compromise with tolerance. They also become more liberal.
(personally, I don’t agree with that – but that’s another story)
>consciously try to form their individual charakter.
charakter = charaCter