【正确答案】正确答案：There is only one difference in sentences A and B. Sentence B uses a more affirmative tone while in sentence A, the words " may" , " It is said" and " seems" show uncertainty about the content of the sentence.(3 points) Appropriate style contributes a lot to an effective academic writing. Appropriate style includes the following characteristics; be consistent; have the right level of formality; express ideas precisely; be concise; be objective; to be specific, the following requirements must be met.(2 points)Firstly, personal pronouns such as "I" , "you" and "we" should be avoided as it will make the writing sound too personal and informal. Secondly, contractions should be avoided in academic writing, as these are the style of spoken or informal English. Thirdly, complex sentences are very common in academic writing. Fourthly, in academic writing, one should avoid the use of vague vocabulary. Fifthly, rhetorical questions should be avoided. Sixthly, one should avoid making statements that assume the reader will take your word that something is true. Last but not least, in academic writing if one wants to quote someone"s words, he should include references to the source of ideas or information in his writing.(7 points) As to the two pair of sentences under discussion, in academic writing, ambiguity should be avoided, and preciseness is necessary, which mean that words such as "may" , "seem" and "it is said" should not appear. Therefore, I will prefer to use sentences B in academic writing.(3 points)

【答案解析】解析：考查论文写作的特点及要求。两组句子之间的不同点在于A句都包含了表示不确定的字眼，如“may”、“seem”以及“It is said”这种表模糊引用的表达。而学术论文要求文风正式，表达严谨，并做到客观公正。具体要求有：避免第一二人称；不使用缩写词；尽量使用复杂句；尽量用名词清晰表达观点，避免出现模棱两可的字眼；任何引用观点都必须注明来源。故而各题中的A句在学术论文中一般不被采用，而B句更符合学术论文的文风。