Writing prompt: My Favorite Teacher

Student essay:
Dear Henery,
I am glad to hear that you get on very well with your maths teacher,Mr Green.Now I'd like to tell you about my favourite teacher.
My favourite teacher is Mr.Shao.He teaches us geography.He is about 27 , I think , and is rather good-looking.He always wears glasses and T-shirt . He has short black hairs and a big smile in his face.
I like him very much. Because he is very friendly . We like friends when we get together.And he is so lovely that just like a boy.He always tells jokes to us in class.I don't think I will bored in Mr.Shao's class.
I still remember once I didn't understand a point in a class.I felt worried and helpless.But Mr.Shao taught me again and again until I got it.Because Mr.Shao I still have a positive attitude to geography.
I am looking forward to hearing from you.
Best wishes!
Yours,
Li Hua

Corrected essay:
Dear Henery,
I am glad to hear that you get on very well with your maths teacher, Mr. Green.
Now I'd like to tell you about my favourite teacher.
My favourite teacher is Mr. Shao. He teaches us geography. He is about 27, I think, and is rather good-looking. He always wears glasses and a T-shirt. He has short black hair and a big smile on his face.
I like him very much because he is very friendly. We are like friends when we get together. And he is so lovely, just like a boy. He always tells jokes to us in class. I don't think I will be bored in Mr. Shao's class.
I still remember once I didn't understand a point in a class. I felt worried and helpless. But Mr. Shao taught me again and again until I got it. Because of Mr. Shao I still have a positive attitude to geography.
I am looking forward to hearing from you.
Best wishes!
Yours,
Li Hua

Error analysis:
error_sentence: Dear Henery,
I am glad to hear that you get on very well with your maths teacher,Mr Green.
correct_sentence: Dear Henery,
I am glad to hear that you get on very well with your maths teacher, Mr. Green.

error: Mr
correction: Mr.
error_type: Contraction Error
error_severity: 1
error_description: Contraction Error: According to English writing conventions, the abbreviation 〈Mr〉 requires a period to indicate a complete abbreviation, therefore it is changed to 『Mr.』 to conform to standard abbreviation rules.
error_sentence: Dear Henery,
I am glad to hear that you get on very well with your maths teacher,Mr Green. Now I'd like to tell you about my favourite teacher.

correct_sentence: Dear Henery,
I am glad to hear that you get on very well with your maths teacher, Mr. Green.

correction: 

error_type: Format Error
error_severity: 3
error_description: Format Error: In formal letter format, different paragraphs need to be separated by a line break, therefore 『』 is added after 〈Mr. Green.〉 to create a blank line between paragraphs.
error_sentence: He always wears glasses and T-shirt .
correct_sentence: He always wears glasses and a T-shirt.
correction: a
error_type: Determiner Error
error_severity: 2
error_description: Determiner Error: The singular countable noun 〈T-shirt〉 needs to be modified by the indefinite article 『a』 to indicate a general T-shirt, therefore 『a』 is added before 〈T-shirt〉 to comply with grammatical rules.
error_sentence: He has short black hairs and a big smile in his face.

correct_sentence: He has short black hair and a big smile on his face.

error: hairs
correction: hair
error_type: Noun Number Error
error_severity: 3
error_description: Noun Number Error: 『hair』 is usually an uncountable noun, referring to hair as a whole; if it is necessary to refer to specific strands of hair, 〈hairs〉 is used, therefore 〈hairs〉 is changed to 『hair』 to conform to English grammar rules.
error_sentence: He has short black hairs and a big smile in his face.

correct_sentence: He has short black hair and a big smile on his face.

error: in
correction: on
error_type: Preposition Error
error_severity: 2
error_description: Preposition Error: According to English grammar rules, when indicating the location of a facial expression, the preposition 『on』 is used in a fixed phrase, therefore 〈in〉 is changed to 『on』 to conform to conventional expression habits.
error_sentence: I like him very much. Because he is very friendly .
correct_sentence: I like him very much because he is very friendly.
error: . Because
correction: because
error_type: Punctuation Error
error_severity: 2
error_description: Punctuation Error: According to English grammar rules, a subordinate clause of reason introduced by 〈Because〉 cannot stand as an independent sentence and needs to be merged with the preceding clause, therefore 〈. Because〉 is changed to 『because』 to make the sentence coherent.
error_sentence: We like friends when we get together.
correct_sentence: We are like friends when we get together.
correction: are
error_type: Verb Choice Error
error_severity: 3
error_description: Verb Choice Error: According to the context, the sentence intends to express that our relationship is like friends when we get together, not that we "like friends"; therefore, 〈like〉 needs to mean similarity, not "to like". Here, 『are like』 should be used to express a comparison or similar relationship, so 『are』 is added before 〈like〉 to clarify the meaning.
error_sentence: And he is so lovely that just like a boy.
correct_sentence: And he is so lovely, just like a boy.
error: that
correction: ,
error_type: Conjunction Error
error_severity: 3
error_description: Conjunction Error: According to English grammar rules, the "so...that" structure should introduce an adverbial clause of result; here the meaning is comparison rather than result, therefore 〈that〉 is deleted and a comma 『,』 is added after 〈lovely〉 to form a more natural sentence structure.
error_sentence: I don't think I will bored in Mr.Shao's class.

correct_sentence: I don't think I will be bored in Mr. Shao's class.

correction: be
error_type: Auxiliary Error
error_severity: 2
error_description: Auxiliary Error: According to English grammar rules, 〈will〉 is usually followed by the base form of a verb; here, 『will be』 is needed to express a future state or situation. The correct structure is 『will be bored』, where 『be』 is the base form of the verb and 〈bored〉 is an adjective indicating the state of being bored, therefore 『be』 is added before 〈bored〉 to clarify the meaning.
error_sentence: Because Mr.Shao I still have a positive attitude to geography.

correct_sentence: Because of Mr. Shao I still have a positive attitude to geography.

correction: of
error_type: Preposition Error
error_severity: 2
error_description: Preposition Error: When 〈Because〉 is followed by a noun phrase, the preposition 『of』 needs to be added to form the fixed phrase 『Because of』, therefore 『of』 is added after 〈Because〉 to comply with grammatical rules.