diff --git a/README.md b/README.md
index a4f20c5..ebc4803 100644
--- a/README.md
+++ b/README.md
@@ -151,6 +151,7 @@
 
 | ISSUE & Pull Requests                          | USER                                                         | Title                                                        |
 | ----------------------------------------------- | ------------------------------------------------------------ | ------------------------------------------------------------ |
+|  [282](https://github.com/Vonng/ddia/pull/282)  |  [@WAangzE](https://github.com/WAangzE)  |   ch2: 更正一处公式问题  |
 |  [281](https://github.com/Vonng/ddia/pull/281)  |  [@lyuxi99](https://github.com/lyuxi99)  |   更正多处内部链接错误  |
 |  [280](https://github.com/Vonng/ddia/pull/280)  |  [@lyuxi99](https://github.com/lyuxi99)  |   ch9: 更正内部链接错误  |
 |  [278](https://github.com/Vonng/ddia/pull/278)  |  [@LJlkdskdjflsa](https://github.com/LJlkdskdjflsa)  |   发现了繁体中文版本中的错误翻译  |
diff --git a/zh-tw/README.md b/zh-tw/README.md
index 29f8838..63d0e46 100644
--- a/zh-tw/README.md
+++ b/zh-tw/README.md
@@ -151,6 +151,7 @@
 
 | ISSUE & Pull Requests                          | USER                                                         | Title                                                        |
 | ----------------------------------------------- | ------------------------------------------------------------ | ------------------------------------------------------------ |
+|  [282](https://github.com/Vonng/ddia/pull/282)  |  [@WAangzE](https://github.com/WAangzE)  |   ch2: 更正一處公式問題  |
 |  [281](https://github.com/Vonng/ddia/pull/281)  |  [@lyuxi99](https://github.com/lyuxi99)  |   更正多處內部連結錯誤  |
 |  [280](https://github.com/Vonng/ddia/pull/280)  |  [@lyuxi99](https://github.com/lyuxi99)  |   ch9: 更正內部連結錯誤  |
 |  [278](https://github.com/Vonng/ddia/pull/278)  |  [@LJlkdskdjflsa](https://github.com/LJlkdskdjflsa)  |   發現了繁體中文版本中的錯誤翻譯  |
diff --git a/zh-tw/ch2.md b/zh-tw/ch2.md
index 742955a..e687f31 100644
--- a/zh-tw/ch2.md
+++ b/zh-tw/ch2.md
@@ -315,11 +315,13 @@ function getSharks() {
 }
 ```
 
-在關係代數中：
+而在關係代數中，你可以這樣寫：
+
 $$
-sharks = σ_{family = "sharks"}(animals)
+sharks = \sigma_{family = "sharks"}(animals)
 $$
-σ（希臘字母西格瑪）是選擇運算子，只返回符合條件的動物，`family="shark"`。
+
+其中 $\sigma$（希臘字母西格瑪）是選擇運算子，只返回符合 `family="shark"` 條件的動物。
 
 定義 SQL 時，它緊密地遵循關係代數的結構：