“that”是英语中使用频率极高的一个词，兼有代词、副词和连词等几个词性，既发挥实词的作用，又担当架构复杂句式的重任。在每年的高考试卷中，that的考查几乎是不可或缺的。
一个that，不同“身份”
请看下面一组句子，你能够辨清that的词性、词义和作用吗？
1. The English spoken in the United States is only slightly different from that spoken in England.
2. —Could you tell me how to get to Victoria Street?
—Victoria Street? That is where the Grand Theatre is.
3. The thought of going back home was all that kept him happy while he was working abroad.
4. A warm thought suddenly came to me that I might use the pocket money to buy some flowers for my mother’s birthday.
5. Pop music is such an important part of society that it has even influenced our language.
6. Roses need special care so that they can live through winter.
7. It was in New Zealand that Elizabeth first met Mr. Smith.
8. Sometimes it was a bit boring to work there because there wasn’t always that much to do.
在上面的几句话中，that分别表示：
1.用作代词，替代前面提到的单数不可数名词或概念，本句中代指the English；
2.用作代词，说明上面刚刚提到的人、事物、想法等，本句中代指Victoria Street；
3.关系代词，在限定性定语从句中代替先行词all，在从句充当主语；
4.从属连词，引导名词性从句，只起连接作用，无具体意义，在本句中是thought的同位语；
5.引导结果状语从句；
6.引导目的状语从句；
7.用于强调句型中，起连接作用；
8.程度副词，等于so。
由于在多个语法结构中，都涉及that的使用，而that又容易与其他相关的词或结构发生混淆，所以要真正掌握that的用法，必须把握好几组词和结构的区别。
把握that，辨清区别
1.that和one，it
在使用作为代词的that时，要区别好它与one和it的区别。请看下面三个题目：
1. The information on the Internet gets around much more rapidly than ___ in the newspaper.
A. it B. those
C. one D. that
2. I prefer a flat in Inveneas to _____in Perth, because I want to live near my Mom’s.
A. one B. that
C. it D. this
3. In my opinion, life in the twenty-first century is much easier than ________.
A. that used to be
B. it is used to
C. it was used to
D. it used to be
答案DAD。that，one和it的区别是：它们均代表前面说过的名词，但that代指单数不可数名词或概念，同类但并非同一个；one代指单数可数名词，同名异物；it代指同名同物。
2.定语从句的that和名词从句的that
定语从句的关系代词that在从句中有语法作用(做主语、宾语等)，而名词从句中的从属连词that只是起连接名词从句的作用，本身没有词义，没有语法作用。因此，区别that到底是引导定语从句还是名词从句，只要看其有没有语法作用即可。例如下面两个题目：
1. Nobody believed the reason _______he explained for being absent from the class.
A. why B that
C. as D. because
2. Nobody believed his reason for being absent from the class _______he had to meet his uncle at the air port.
A. why B that
C. where D. because
答案BB。第一个句子是定语从句，that代替先行词reason，在从句中作宾语(he explained the reason)；第二个句子是名词从句，that引导的从句做reason的同位语，是进一步说明reason的内容，that只起连接从句的作用，在从句中不担当任何成分。
3.高度警惕的几个陷阱
你不妨先试着回答下面几个题目：
1. Harry Potter is such an interesting book _____ everybody likes to read.
A. that B. as
C. which D. /
2. It was along the Mississippi River ____ Mark Twain spent much of his childhood.
A. how B. which
C. that D. where
3. It was evening we reached the little town of Winchester.
A. that B. until
C. since D. before
4.—— Where did you get to know her?
—— It was on the farm______we worked.
A. that B. where
C. which D. there
5.—— He got his first book published. It turned out to be a bestseller.
—— When was that?
—— It was in 2000 ______he was still in college.
A. that B. then
C. which D. when
你的答案是不是ACAAA？如果是这样，那你只回答对了第二个题目，而另外的四个题都错了，因为它们都与that无关，这是最典型的陷阱题。我们不妨来仔细分析一下：
第一题，你想选择that，那你一定是认为这是个结果状语从句，而that后面everybody likes to read少了“it”，因此，这不是状语从句，而是由as引导的限定性定语从句。
第二题选择that，是It was…that…的强调句。因为去掉这个结构，所保留的是个完整语句，即：Mark Twain spent much of his childhood along the Mississippi River，只不过使用强调结构来突出地点“along the Mississippi River”。但是，你如果还是以强调句的惯性思维来回答第三至第五题，你不免就犯了“经验主义”的错误，因为这三个，如果是强调句的话，在去掉强调结构后，都不是正确的、或不符合上下文语境的句子：即
3.We reached the little town of Winchester evening.(evening前少介词)
4.—— Where did you get to know her?
—— we worked on the farm.(答非所问)
5.—— He got his first book published. It turned out to be a bestseller.
—— When was that?
—— he was still in college in 2000. (答非所问)
从上面的分析不难看出，第三题是个时间状语从句选择before，第四第五都是定语从句，分别选择where(关系副词，地点)，when(关系副词，时间)。上面五个题的正确答案应当是BCDBD。
英语中像that这样的高频用词和高考热点的词还有很多，我们会陆续给同学们介绍。在复习中，要特别注意知识点的横向联系，把词在不同语法结构中的作用做一个集中梳理，对大家学习和巩固知识非常有用。(南开中学 段胜利)