Writing prompt: Based on the given hints and referring to the picture, write a short essay.
Last Sunday, I went for a picnic in the park with my friends. It started raining in the afternoon. I forgot my umbrella and got wet. I felt cold and had a headache. My friends took me to the hospital. The doctor said I had a fever. He gave me some medicine and told me to go home and rest well.
Writing hints: picnic; rain; umbrella; get wet; hospital; fever; medicine.

Student essay:
Last weekend, I with my friends go to the picnic. At the beginning of rain in the afternoon, but I not take umbrella. I feel very cold and headache.

Corrected essay:
Last weekend, I went for a picnic with my friends. It began to rain in the afternoon, but I did not take an umbrella. I felt very cold and had a headache.

Error analysis:
error_sentence: Last weekend, I with my friends go to the picnic.
correct_sentence: Last weekend, I went for a picnic with my friends.
correction: went for a picnic
error_type: Word Order Error
error_severity: 4
error_description: ① Word Order Error: According to sentence structure, the main clause should follow the subject-verb-object structure, and the complement part led by "with" should be placed after, so 〈with my friends〉 needs to be placed after the verb-object structure, changing it to the correct grammatical structure of "subject + predicate verb phrase + with + others", changing 〈I with my friends go to the picnic〉 to 『I went for a picnic with my friends』; ② Verb Tense Error: The time adverbial is 〈Last weekend〉, so 〈go〉 needs to be changed to the past tense 『went』; ③ Preposition Error: 〈go to the picnic〉 does not conform to common English expression; the preposition 'to' should be changed to 'for', modifying it to 『went for a picnic』 to mean "go for a picnic".
error_sentence: Last weekend, I with my friends go to the picnic. At the beginning of rain in the afternoon, but I not take umbrella.
correct_sentence: Last weekend, I went for a picnic with my friends. It began to rain in the afternoon, but I did not take an umbrella.
error: go to the picnic. At the beginning of
correction: . It began to
error_type: Word Order Error
error_severity: 4
error_description: ① Word Order Error: According to the original sentence structure, the predicate verb phrase 〈go to the picnic〉 should be placed after the subject "I"; ② Sentence Structure Error: The structure 〈At the beginning of rain〉 is incomplete, lacking a subject-verb structure; it should be changed to 『It began to rain』 using an expletive subject structure to indicate "it started raining".
error_sentence: At the beginning of rain in the afternoon, but I not take umbrella.
correct_sentence: It began to rain in the afternoon, but I did not take an umbrella.
correction: did
error_type: Auxiliary Error
error_severity: 3
error_description: Auxiliary Error: According to English grammar rules, the past tense negative sentence requires the auxiliary verb 〈did〉 to form the negative structure, so 『did』 should be added before 〈not take〉 to form 『did not take』.
error_sentence: At the beginning of rain in the afternoon, but I not take umbrella.
correct_sentence: It began to rain in the afternoon, but I did not take an umbrella.
correction: an
error_type: Determiner Error
error_severity: 3
error_description: Determiner Error: According to English grammar rules, the noun 〈umbrella〉 is a singular countable noun and requires the article 〈an〉 for determination, so 『an』 should be added before 〈umbrella〉.
error_sentence: I feel very cold and headache.
correct_sentence: I felt very cold and had a headache.
error: feel
correction: felt
error_type: Verb Tense Error
error_severity: 3
error_description: Verb Tense Error: According to the prompt requirements, the essay needs to use the simple past tense to describe past events; the verb 〈feel〉 needs to be changed to the past tense 『felt』 to maintain tense consistency.
error_sentence: I feel very cold and headache.
correct_sentence: I felt very cold and had a headache.
correction: had a
error_type: Verb Choice Error
error_severity: 4
error_description: ① Verb Choice Error: The original sentence lacks a verb for 〈headache〉 to express the action; 『had』 needs to be added to form a complete sentence; ② Determiner Error: The noun 〈headache〉 requires the article 〈a〉 for determination, so 『a』 needs to be added to conform to English expression habits.