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 Sunday, I had a picnic with my friends in the park. In the afternoon, it was rain. I hadn't got umbrella, so I got wet. I felt cold and had got a headache. My friends went to the hospital with me. The doctor sad I have got fever, and he give me medicine. I had a rest.

Corrected essay:
Last Sunday, I had a picnic with my friends in the park. In the afternoon, it was rainy. I hadn't got an umbrella, so I got wet. I felt cold and had a headache. My friends went to the hospital with me. The doctor said I had got a fever, and he gave me some medicine. I had a rest.

Error analysis:
error_sentence: In the afternoon, it was rain.
correct_sentence: In the afternoon, it was rainy.
error: rain
correction: rainy
error_type: PoS Confusion Error
error_severity: 2
error_description: PoS Confusion Error: According to English grammar rules, the linking verb 〈was〉 requires an adjective as a predicative; therefore, the noun 〈rain〉 should be changed to the adjective 『rainy』 to conform to English grammar.
error_sentence: I hadn't got umbrella, so I got wet.
correct_sentence: I hadn't got an umbrella, so I got wet.
correction: an
error_type: Determiner Error
error_severity: 2
error_description: Determiner Error: According to English grammar rules, a singular countable noun must be preceded by an indefinite article; the necessary determiner 『an』 is missing before 〈umbrella〉 in the original sentence, therefore, the phrase is modified to 『got an umbrella』 to comply with English grammar rules.
error_sentence: I felt cold and had got a headache.
correct_sentence: I felt cold and had a headache.
error: got
error_type: Word Redundancy Error
error_severity: 4
error_description: Word Redundancy Error: According to English expression conventions, 〈had〉 already clearly expresses the past action, making 〈got〉 redundant here; its removal does not affect the sentence's meaning, thus 〈had got a headache〉 is simplified to 『had a headache』 for conciseness.
error_sentence: The doctor sad I have got fever, and he give me medicine.
correct_sentence: The doctor said I had got a fever, and he gave me some medicine.
error: sad I have got
correction: said I had got a
error_type: Verb Tense Error
error_severity: 5
error_description: ① Spelling Error: Based on the sentence meaning, the intention is to express 'said', thus 〈sad〉 is a misspelling of 『said』 and needs correction to 『said』 for clarity; ② Determiner Error: According to English grammar rules, a singular countable noun must be preceded by an indefinite article; the necessary determiner 『a』 is missing before 〈fever〉 in the original sentence, therefore, the phrase is modified to 『had a fever』 to comply with English grammar rules; ③ Verb Tense Error: According to the context, the past perfect tense should be used, therefore 〈have〉 needs to be changed to 『had』 to fit the context.
error_sentence: The doctor sad I have got fever, and he give me medicine.
correct_sentence: The doctor said I had got a fever, and he gave me some medicine.
error: give me
correction: gave me some
error_type: Verb Tense Error
error_severity: 4
error_description: ① Verb Tense Error: According to the prompt, 'Last Sunday' describes a past event, requiring the simple past tense; the original sentence uses the simple present 〈give〉, which should be changed to the simple past 『gave』 to fit the context; ② Determiner Error: According to English grammar rules, the uncountable noun 〈medicine〉 requires 『some』 before it to indicate an indefinite quantity and conform to English expression conventions, thus 『some』 should be added before 〈medicine〉.