Hello. I am a teenager and 16 years old. I finished the seco

Hello. I am a teenager and 16 years old. I finished the secondary school months ago. My English skills are poor though I love it. I practiced it (a bit), but I am very upset when I saw the marks in the texts I got. The language mistakes were so small that I could not find and fix it and therefore got low points. My attempts at ridding my mind of problems of all kinds were always failed. The carelessness and unknown things like air around the body cannot be removed. I am torn apart! Maybe you can give me plenty of proposals and help solve the followings:
Firstly: Prep. . I don't know which prep. should I use before or after a word. Sometimes I know the relationship, but after a short time forget it. For example, I did not know if use "on" or "in" at the left of the sentence "the summer of 2012" in the last exam.
Secondly: Verbs. After I understand a verb, I usually do not know the usage of it. When a prep. matches it, they could get more meanings and the appearance of the word after or between them will be altered. Sometimes I know their relationship, however, do not understand how should the appearance of the word be changed.
Thirdly: Speaking skills. I always do a lot of thinking when I want to say some sentences in English. It usually costs me so much time and lets me spend a lot of brain cells. I must change my meanings into foreign language and then change sentences in foreign language into English unlike the other people using my language.
How can I achieve English high marks immediately? I NEED YOUR HELP!
on the left side of the sentence. I've got a prepositional mistake.
It is good of you to point the errors in the article out!

Hello.I am a 16-year-old teenager.I finished the secondary school months ago.My English are poor though I love it.I practiced it (a bit),but I was very upset when I saw the marks in the texts I got.The linguistic mistakes were so small that I could not find and fix them,therefore I got low points.My attempts at ridding my mind of problems of all kinds have always failed.The carelessness and unknown things like air around the body cannot be removed.I am torn apart!Maybe you can give me some pieces of advice and help me solve the followings:
Firstly:Prep..I don't know which prep.should I use before or after a word.I know the relationship,but Sometimes I forget it.For example,I did not know if I should use "on" or "in" at the left of the sentence "the summer of 2012" in the last exam.
Secondly:Verbs.After I understand a verb,I usually do not know how to us it.When a prep.matches it,they could get more meanings and the appearance of the word after or between them will be altered.Sometimes I know their relationship,however,I do not understand how the appearance of the word should be changed.
Thirdly:Speaking skills.I always do a lot of thinking when I want to say some sentences in English.It usually costs me so much time and lets me spend a lot of brain cells.I must change my meanings into foreign language and then change sentences in foreign language into English unlike the other people using my language.
你初中能写出这么顺畅的字句来,很不错啊.再接再厉吧.
对于你说的时间介词的运用,指出具体某一天的就是on,大于这个范围的都是用in了.
你缺少一些逻辑思维的锻炼,可以找一本《普通逻辑》来看看.