Writing prompt: Using the information provided in Chinese and referring to the picture, write a short essay.
Mr. Cool's Clothes Store is having a big sale with great discounts. Sweaters in various colors are only 30 yuan, shorts are only 20 yuan, and shirts are only 25 yuan. Large bags sell for 35 yuan, and small bags for 20 yuan. There are also many beautiful shoes and skirts available. Welcome to shop.

Student essay:
Mr. Cool's Clothes Store is on sale now. It has a great price. It's only 30 yuan for a sweater in any color. It's 20 yuan each pair for shorts. It's only 25 yuan for shirts. Big handbags are 35 yuan while 20 yuan for small ones. There are also many beautiful shoes and dresses. Welcome to our store.

Corrected essay:
Mr. Cool's Clothes Store is on sale now. It has great prices. It's only 30 yuan for a sweater in any color. It's 20 yuan for each pair of shorts. It's only 25 yuan for shirts. Big handbags are 35 yuan while small ones are 20 yuan. There are also many beautiful shoes and dresses. Welcome to our store.

Error analysis:
error_sentence: It has a great price.
correct_sentence: It has great prices.
error: a great price
correction: great prices
error_type: Noun Number Error
error_severity: 4
error_description: ① Determiner Error: Since the promotion involves multiple item prices, the indefinite article 〈a〉 in the original phrase 『a great price』 does not fit the plural context; according to English grammar rules, 〈a〉 should be deleted and adjusted to a plural determiner structure, thus modified to 『great prices』 to maintain number consistency and accuracy in the business context; ② Noun Number Error: Based on the business context and the need to express the sentence meaning, when a store promotion involves multiple items, 'price' should be a plural concept; therefore, the singular noun 〈price〉 is corrected to the plural form 『prices』 to accurately reflect the reality of multiple items and multiple prices.
error_sentence: It's 20 yuan each pair for shorts.
correct_sentence: It's 20 yuan for each pair of shorts.
correction: for
error_type: Preposition Error
error_severity: 2
error_description: Preposition Error: According to English price expression norms, the preposition 『for』 is needed to connect the amount and the item to form a complete price structure. The original sentence lacks the necessary preposition, resulting in an incomplete sentence structure; therefore, 『for』 is added to form the standard price expression, correcting the fragment to 『20 yuan for each pair』.
error_sentence: It's 20 yuan each pair for shorts.
correct_sentence: It's 20 yuan for each pair of shorts.
error: for
correction: of
error_type: Preposition Error
error_severity: 2
error_description: Preposition Error: According to English fixed phrase structure rules, 〈each pair of shorts〉 as a standard quantifier phrase must use the preposition 『of』 to indicate the possessive relationship of 'a pair of shorts'. The misuse of 〈for〉 was detected as not conforming to the standard collocation of this phrase; therefore, the incorrect preposition 〈for〉 is replaced with the correct preposition 『of』, fully correcting it to 『each pair of shorts』.
error_sentence: Big handbags are 35 yuan while 20 yuan for small ones.
correct_sentence: Big handbags are 35 yuan while small ones are 20 yuan.
error: 20 yuan for
error_type: Word Redundancy Error
error_severity: 3
error_description: Word Redundancy Error: According to contextual semantic analysis, the price structure 〈20 yuan for〉 forms a repetitive statement with the subsequent explicit mention of the 'small bag price'. Based on the principle of conciseness in English writing, the redundant part is deleted to optimize the sentence structure.
error_sentence: Big handbags are 35 yuan while 20 yuan for small ones.
correct_sentence: Big handbags are 35 yuan while small ones are 20 yuan.
correction: are 20 yuan
error_type: Sentence Structure Error
error_severity: 3
error_description: Sentence Structure Error: According to the grammatical rules of English contrastive sentence structures, parallel clauses need to maintain structural symmetry. The original sentence lacks a predicate verb, making the second clause incomplete; therefore, the linking verb 『are』 and the price phrase 『20 yuan』 are added to form a complete predicate, correcting the fragment to 『small ones are 20 yuan』 to fully express the price information for the small bags.