下面是2013年9月21日的SAT官方每日一题的内容，是关于写作方面的，题型是句子改错。SAT官方每日一题是collegeboard每天都会发布的题目，关于SAT考试的三个部分的各个题型。下面我们就一起来看一下这个SAT官方每日一题吧。

　　SAT官方每日一题之写作---句子改错：

　　Writing > Identifying Sentence Errors

　　The following sentence contains either a single error or no error at all. If the sentence contains an error, select the one underlined part that must be changed to make the sentence correct. If the sentence contains no error, select choice E.

　　A(Once) the suspension bridge replaced the cantilever, the United States B(becomes) the world leaderC(in this new) D(type of) long-span bridgebuilding. E(No error)

　　(A) A

　　(B) B

　　(C) C

　　(D) D

　　(E) E

　　The correct answer is B

　　Explanation

　　The error in this sentence occurs at (B), where there is an inappropriate verb form. To match the past tense established and used elsewhere in the sentence (“Once,” “replaced”), the past-tense “became” is needed.

　　下面是一道和SAT官方每日一题相似的题目，供大家练习：

　　A(It weaves) across a strip of tropical land B(where) the Isthmus of Panama C(narrows) in the shape of a long flattened letter S, the Panama Canal D(links the Atlantic and) Pacific Oceans. E(No error)

　　Answer Choices

　　(A) A

　　(B) B

　　(C) C

　　(D) D

　　(E) E

　　The correct answer is A

　　Explanation

　　The error in this sentence occurs at (A), where a comma splice is created. To fix the comma splice, “It weaves” should be changed to “Weaving.”

　　以上就是关于2013年9月21日SAT官方每日一题中写作句子改错部分的详细内容，包括了题目和选项以及答案，后面附有一道相关的练习题。大家可以在备考SAT的过程中关注SAT每日一题的内容，这样就可以更好有不间断的练习，也就能在日积月累的过程中得到提高。