Missing My Teenager Days　

I normally take a bus to go home after work (you don't need to say 'to go' - in this sentence, it's implied that you ride the bus 'to go' somewhere! :)) . On the bus, I like to perceive the people standing around me and to guess what their life would be. Today, when I went on the bus, I saw several teenagers wearing school uniforms standing close to the back window (it's either 'they stood near/on/close to X', or they're standing near/on/close to X. As you used 'wearing' earlier on in the sentence, it's good to stick to -ing tense!) . They were talking about some tests they were taking today.A fat boy laughed at a tall boy, since the tall boy made a low-level mistake in the physical exam. The tall boy wasn't upset at all; he said it will be easy for him to get the No.1 score next time. Two girl female classmates standing near them also commented on the exams and talked about their study plans (usually, 'girl' or 'boy' are used as nouns - to describe the classmates gender, use 'male' or 'female'). There is one moment, At this moment/in this moment, I found myself very envious of them so much that as they are in at such a beautiful age and they can plan and fight for their future with no life burden (In this sentence, to say 'there is one moment' doesn't quiet work, because you're talking about the experience as it happened - therefore, to say 'there is one moment' is a little disjointed. 'At this moment' links the story a little better! Also, you are talking 'envy' is a noun - as you are feeling envy, it needs to change to the verb form 'envious'. Furthermore, you shouldn't say you felt 'envious so much'; the quantifier must come before the verb - so you felt 'very envious' or you 'felt so much envy. Finally, it is not usually said that you are in an age, because you're not inside it - you are at an age. Hope this all makes sense!!) They have plenty of time and youth to study anything they are interested in, to date anyone they fall in love with, to make friends with anyone they like.

When I got off the bus, the teenagers are were still there (this story is past tense, so we need to use 'were' rather than 'are'). I know youth will never come back and chase after you. We shall live in the moment.

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-  hope all these corrections make sense! I'm sorry if my descriptions of why the changes are important is difficult to understand. I think that your english is very good, though! Well done! :)

[Please correct]Missing the teenager days

I normally take a bus to go home after work. On the bus, I like to perceive the people standing around me and to guess what their life would be.

On the bus, I like to look at the people standing around me a guess what their lives are like.

Today, when I went on the bus, I saw several teenagers wearing school uniforms standing close to the back window.

They were talking about some tests they were taking today.

They were talking about some tests they had taken today.

A fat boy laughed at a tall boy, since because the tall boy made a low-level simple mistake in the physical exam.

The tall boy wasn't upset at all; he said it will be easy for him to get the No.1 score next time.

Two girl classmates standing near them also commented on the exams and talked about their study plans.

There is one moment, I found myself envy them so much that they are in such a beautiful age and they can plan and fight for their future with no life burden.

That moment, I found myself envying them so much. They are at an age where they can plan and strive for their future without any burdens.

They have plenty of time and in their youth to study anything they are interested in, to date anyone they fall in love with and to make friends with anyone they like.

When I got off the bus, the teenagers are were still there aboard. I know youth will never come back and chase after you. We shall live in that moment.