Writing prompt: My Dream

Student essay:
Every one has a dream.My dream is to be a doctor in the future.
Doctors are nice and kind. They devote all their lives to helping patients. They are always dressed in white, so we regard them as White Angels.
It is said that doctors are always tired and busy working in the hospital , but it can't obstruct me in realizing my dream. I'll study harder and read more books about medical science. No matter how difficult, i will never give up my dream. Why do I want to be a doctor?Because I want to save more lives.
I believe my dream can come true,if I study harder.

Corrected essay:
Everyone has a dream. My dream is to be a doctor in the future.
Doctors are nice and kind. They devote all their lives to helping patients. They are always dressed in white, so we regard them as White Angels.
It is said that doctors are always tired and busy working in the hospital, but it can't obstruct me from realizing my dream. I'll study harder and read more books about medical science. No matter how difficult it is, I will never give up my dream. Why do I want to be a doctor? Because I want to save more lives.
I believe my dream can come true if I study harder.

Error analysis:
error_sentence: Every one has a dream.
correct_sentence: Everyone has a dream.
error: Every one
correction: Everyone
error_type: Noun Error
error_severity: 3
error_description: Noun Error: 〈Every one〉 are two separate words, but here it needs to express the meaning of 'everyone'. According to English grammar rules, the word 『Everyone』 should be used, merging the determiner 〈every〉 and the noun 〈one〉 into a single pronoun.
error_sentence: It is said that doctors are always tired and busy working in the hospital , but it can't obstruct me in realizing my dream.
correct_sentence: It is said that doctors are always tired and busy working in the hospital, but it can't obstruct me from realizing my dream.
error: in
correction: from
error_type: Preposition Error
error_severity: 3
error_description: Preposition Error: According to English grammar rules, the fixed collocation for the verb 〈obstruct〉 is 〈obstruct someone from doing something〉, meaning 'to prevent someone from doing something', therefore the preposition 〈in〉 needs to be changed to 『from』 to comply with the grammatical rules of the phrasal verb.
error_sentence: No matter how difficult, i will never give up my dream.
correct_sentence: No matter how difficult it is, I will never give up my dream.
error: , i
correction: it is, I
error_type: Sentence Structure Error
error_severity: 4
error_description: ① Sentence Structure Error: According to English grammar rules, 〈No matter how difficult〉 is an incomplete adverbial clause, lacking a subject and a linking verb; 『it is』 needs to be added to complete the clause structure; ② Case Error: According to English writing conventions, the personal pronoun 〈i〉 should be capitalized as 『I』 to mean 'I'.
error_sentence: Why do I want to be a doctor?Because I want to save more lives.

correct_sentence: Why do I want to be a doctor? Because I want to save more lives.

error: doctor?Because
correction: doctor? Because
error_type: Punctuation Error
error_severity: 2
error_description: Punctuation Error: According to English writing conventions, a space should be kept between a question and its answer. A space should be added after the question mark 〈?〉, changing the run-on structure 〈?Because〉 to 『? Because』 to comply with English punctuation rules.
error_sentence: I believe my dream can come true,if I study harder.
correct_sentence: I believe my dream can come true if I study harder.
error: ,
error_type: Punctuation Error
error_severity: 2
error_description: Punctuation Error: According to English grammar rules, no comma is needed to separate the conditional adverbial clause 〈if I study harder〉 from the main clause. Delete the redundant comma to make the compound sentence structure more compliant with formal written expression standards.