diff --git a/webmagic-core/src/main/java/us/codecraft/webmagic/selector/PlainText.java b/webmagic-core/src/main/java/us/codecraft/webmagic/selector/PlainText.java
index d06a531..6fabd99 100644
--- a/webmagic-core/src/main/java/us/codecraft/webmagic/selector/PlainText.java
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/selector/PlainText.java
@@ -6,10 +6,11 @@ import java.util.ArrayList;
 import java.util.List;
 
 /**
- * 可抽取的纯文本，不包括xpath和css selector实现。<br>
+ * Selectable plain text.<br>
+ * Can not be selected by XPath or CSS Selector.
+ *
  * @author code4crafter@gmail.com <br>
- * Date: 13-4-21
- * Time: 上午7:54
+ * @since 0.1.0
  */
 public class PlainText implements Selectable {
 
@@ -59,7 +60,7 @@ public class PlainText implements Selectable {
         List<String> results = new ArrayList<String>();
         for (String string : strings) {
             String result = selector.select(string);
-            if (result!=null){
+            if (result != null) {
                 results.add(result);
             }
         }
diff --git a/webmagic-core/src/main/java/us/codecraft/webmagic/utils/Experimental.java b/webmagic-core/src/main/java/us/codecraft/webmagic/utils/Experimental.java
index 265f869..2022d29 100644
--- a/webmagic-core/src/main/java/us/codecraft/webmagic/utils/Experimental.java
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/utils/Experimental.java
@@ -1,8 +1,8 @@
 package us.codecraft.webmagic.utils;
 
 /**
+ * Stands for features unstable.
  * @author code4crafter@gmail.com <br>
- * Stands for features not stable.
  */
 public @interface Experimental {
 }
diff --git a/webmagic-core/src/main/java/us/codecraft/webmagic/utils/FilePersistentBase.java b/webmagic-core/src/main/java/us/codecraft/webmagic/utils/FilePersistentBase.java
index 509a71f..e65e2f9 100644
--- a/webmagic-core/src/main/java/us/codecraft/webmagic/utils/FilePersistentBase.java
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/utils/FilePersistentBase.java
@@ -3,11 +3,10 @@ package us.codecraft.webmagic.utils;
 import java.io.File;
 
 /**
- * 文件持久化的基础类。<br>
+ * Base object of file persistence.
  *
  * @author code4crafter@gmail.com <br>
- *         Date: 13-8-11 <br>
- *         Time: 下午4:21 <br>
+ * @since 0.2.0
  */
 public class FilePersistentBase {
 
diff --git a/webmagic-core/src/main/java/us/codecraft/webmagic/utils/ThreadUtils.java b/webmagic-core/src/main/java/us/codecraft/webmagic/utils/ThreadUtils.java
index d6876c7..0d5666c 100644
--- a/webmagic-core/src/main/java/us/codecraft/webmagic/utils/ThreadUtils.java
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/utils/ThreadUtils.java
@@ -6,10 +6,8 @@ import java.util.concurrent.ThreadPoolExecutor;
 import java.util.concurrent.TimeUnit;
 
 /**
- * 线程工具类。<br>
  * @author code4crafer@gmail.com
- *         Date: 13-6-23
- *         Time: 下午7:11
+ * @since 0.1.0
  */
 public class ThreadUtils {
 
diff --git a/webmagic-core/src/main/java/us/codecraft/webmagic/utils/UrlUtils.java b/webmagic-core/src/main/java/us/codecraft/webmagic/utils/UrlUtils.java
index 9f038bc..7dae1f2 100644
--- a/webmagic-core/src/main/java/us/codecraft/webmagic/utils/UrlUtils.java
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/utils/UrlUtils.java
@@ -6,20 +6,20 @@ import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
 /**
- * url及html处理工具类。<br>
+ * url and html utils.
+ *
  * @author code4crafter@gmail.com <br>
- * Date: 13-4-21
- * Time: 下午1:52
+ * @since 0.1.0
  */
 public class UrlUtils {
 
     private static Pattern relativePathPattern = Pattern.compile("^([\\.]+)/");
 
     /**
-     * 将url想对地址转化为绝对地址
-     * @param url url地址
-     * @param refer url地址来自哪个页面
-     * @return url绝对地址
+     * canonicalizeUrl
+     * @param url
+     * @param refer
+     * @return canonicalizeUrl
      */
     public static String canonicalizeUrl(String url, String refer) {
         if (StringUtils.isBlank(url) || StringUtils.isBlank(refer)) {
diff --git a/webmagic-core/src/main/java/us/codecraft/webmagic/utils/package.html b/webmagic-core/src/main/java/us/codecraft/webmagic/utils/package.html
index bfbe8df..6b970ee 100644
--- a/webmagic-core/src/main/java/us/codecraft/webmagic/utils/package.html
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/utils/package.html
@@ -1,5 +1,5 @@
 <html>
 	<body>
-提供一些处理链接的静态工具类。
+Static utils of webmagic.
 	</body>
 </html>