diff --git a/webmagic-extension/src/main/java/us/codecraft/webmagic/MultiPageModel.java b/webmagic-extension/src/main/java/us/codecraft/webmagic/MultiPageModel.java
index e3411fc..88caf3e 100644
--- a/webmagic-extension/src/main/java/us/codecraft/webmagic/MultiPageModel.java
+++ b/webmagic-extension/src/main/java/us/codecraft/webmagic/MultiPageModel.java
@@ -8,6 +8,7 @@ import java.util.Collection;
  * Extract an object of more than one pages, such as news and articles。<br>
  *
  * @author code4crafter@gmail.com <br>
+ * @since 0.2.0
  */
 @Experimental
 public interface MultiPageModel {
diff --git a/webmagic-extension/src/main/java/us/codecraft/webmagic/model/AfterExtractor.java b/webmagic-extension/src/main/java/us/codecraft/webmagic/model/AfterExtractor.java
index 5b74309..91c603f 100644
--- a/webmagic-extension/src/main/java/us/codecraft/webmagic/model/AfterExtractor.java
+++ b/webmagic-extension/src/main/java/us/codecraft/webmagic/model/AfterExtractor.java
@@ -3,9 +3,10 @@ package us.codecraft.webmagic.model;
 import us.codecraft.webmagic.Page;
 
 /**
- * 实现这个接口即可在抽取后进行后处理。<br>
+ * Interface to be implemented by page models that need to do something after fields are extracted。<br>
  *
  * @author code4crafter@gmail.com <br>
+ * @since 0.2.0
  */
 public interface AfterExtractor {
 
diff --git a/webmagic-extension/src/main/java/us/codecraft/webmagic/model/ConsolePageModelPipeline.java b/webmagic-extension/src/main/java/us/codecraft/webmagic/model/ConsolePageModelPipeline.java
index c841f10..abf411c 100644
--- a/webmagic-extension/src/main/java/us/codecraft/webmagic/model/ConsolePageModelPipeline.java
+++ b/webmagic-extension/src/main/java/us/codecraft/webmagic/model/ConsolePageModelPipeline.java
@@ -4,9 +4,10 @@ import org.apache.commons.lang3.builder.ToStringBuilder;
 import us.codecraft.webmagic.Task;
 
 /**
+ * Print page model in console.<br>
+ * Usually used in test.<br>
  * @author code4crafter@gmail.com <br>
- * Date: 13-8-3 <br>
- * Time: 下午3:41 <br>
+ * @since 0.2.0
  */
 public class ConsolePageModelPipeline implements PageModelPipeline {
     @Override
diff --git a/webmagic-extension/src/main/java/us/codecraft/webmagic/model/Extractor.java b/webmagic-extension/src/main/java/us/codecraft/webmagic/model/Extractor.java
index 0494076..32f561e 100644
--- a/webmagic-extension/src/main/java/us/codecraft/webmagic/model/Extractor.java
+++ b/webmagic-extension/src/main/java/us/codecraft/webmagic/model/Extractor.java
@@ -3,9 +3,9 @@ package us.codecraft.webmagic.model;
 import us.codecraft.webmagic.selector.Selector;
 
 /**
+ * The object contains 'ExtractBy' information.
  * @author code4crafter@gmail.com <br>
- * Date: 13-8-1 <br>
- * Time: 下午9:48 <br>
+ * @since 0.2.0
  */
 class Extractor {
 
diff --git a/webmagic-extension/src/main/java/us/codecraft/webmagic/model/FieldExtractor.java b/webmagic-extension/src/main/java/us/codecraft/webmagic/model/FieldExtractor.java
index 4ec1bbc..600e184 100644
--- a/webmagic-extension/src/main/java/us/codecraft/webmagic/model/FieldExtractor.java
+++ b/webmagic-extension/src/main/java/us/codecraft/webmagic/model/FieldExtractor.java
@@ -6,18 +6,18 @@ import java.lang.reflect.Field;
 import java.lang.reflect.Method;
 
 /**
+ * Wrapper of field and extractor.
  * @author code4crafter@gmail.com <br>
- * Date: 13-8-1 <br>
- * Time: 下午9:48 <br>
+ * @since 0.2.0
  */
-class FieldExtractor extends Extractor{
+class FieldExtractor extends Extractor {
 
     private final Field field;
 
     private Method setterMethod;
 
-    public FieldExtractor(Field field, Selector selector, Source source, boolean notNull,boolean multi) {
-        super(selector, source, notNull,multi);
+    public FieldExtractor(Field field, Selector selector, Source source, boolean notNull, boolean multi) {
+        super(selector, source, notNull, multi);
         this.field = field;
     }
 
diff --git a/webmagic-extension/src/main/java/us/codecraft/webmagic/model/HasKey.java b/webmagic-extension/src/main/java/us/codecraft/webmagic/model/HasKey.java
index dd9ace2..3a8e6e2 100644
--- a/webmagic-extension/src/main/java/us/codecraft/webmagic/model/HasKey.java
+++ b/webmagic-extension/src/main/java/us/codecraft/webmagic/model/HasKey.java
@@ -1,18 +1,18 @@
 package us.codecraft.webmagic.model;
 
+import us.codecraft.webmagic.model.annotation.Experimental;
+
 /**
- * 标志一个Model的key。<br>
- * 实现了这个接口的Model在输出时会使用getKey()作为标志(例如JsonFilePageModelPipeline中持久化的文件名)。<br>
- * 如果持久化的文件名是乱码，请再运行的环境变量里加上LANG=zh_CN.UTF-8 。<br>
- *
+ * Interface to be implemented by page mode.<br>
+ * Can be used to identify a page model, or be used as name of file storing the object.<br>
  * @author code4crafter@gmail.com <br>
- *         Date: 13-8-10 <br>
- *         Time: 上午7:39 <br>
+ * @since 0.2.0
  */
+@Experimental
 public interface HasKey {
 
     /**
-     * 在输出时会使用key作为标志(例如JsonFilePageModelPipeline中持久化的文件名)。
+     *
      *
      * @return key
      */
diff --git a/webmagic-extension/src/main/java/us/codecraft/webmagic/model/ModelPageProcessor.java b/webmagic-extension/src/main/java/us/codecraft/webmagic/model/ModelPageProcessor.java
index af762ec..8a40dae 100644
--- a/webmagic-extension/src/main/java/us/codecraft/webmagic/model/ModelPageProcessor.java
+++ b/webmagic-extension/src/main/java/us/codecraft/webmagic/model/ModelPageProcessor.java
@@ -14,10 +14,10 @@ import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
 /**
- * 基于PageProcessor的扩展点。<br>
+ * The extension to PageProcessor for page model extractor.
+ *
  * @author code4crafter@gmail.com <br>
- * Date: 13-8-1 <br>
- * Time: 下午8:46 <br>
+ * @since 0.2.0
  */
 class ModelPageProcessor implements PageProcessor {
 
diff --git a/webmagic-extension/src/main/java/us/codecraft/webmagic/model/ModelPipeline.java b/webmagic-extension/src/main/java/us/codecraft/webmagic/model/ModelPipeline.java
index 07d6c5a..071cb26 100644
--- a/webmagic-extension/src/main/java/us/codecraft/webmagic/model/ModelPipeline.java
+++ b/webmagic-extension/src/main/java/us/codecraft/webmagic/model/ModelPipeline.java
@@ -11,11 +11,10 @@ import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 
 /**
- * 基于Pipeline的扩展点，用于实现注解格式的Pipeline。<br>
- * 与PageModelPipeline是一对多的关系(原谅作者没有更好的名字了)。<br>
+ * The extension to Pipeline for page model extractor.
+ *
  * @author code4crafter@gmail.com <br>
- * Date: 13-8-2 <br>
- * Time: 上午10:47 <br>
+ * @since 0.2.0
  */
 class ModelPipeline implements Pipeline {
 
diff --git a/webmagic-extension/src/main/java/us/codecraft/webmagic/model/OOSpider.java b/webmagic-extension/src/main/java/us/codecraft/webmagic/model/OOSpider.java
index e04a30d..cbfd50f 100644
--- a/webmagic-extension/src/main/java/us/codecraft/webmagic/model/OOSpider.java
+++ b/webmagic-extension/src/main/java/us/codecraft/webmagic/model/OOSpider.java
@@ -42,7 +42,7 @@ public class OOSpider extends Spider {
     }
 
     /**
-     * 创建一个爬虫。<br>
+     * create a spider
      * @param site
      * @param pageModelPipeline
      * @param pageModels
diff --git a/webmagic-extension/src/main/java/us/codecraft/webmagic/model/PageModelExtractor.java b/webmagic-extension/src/main/java/us/codecraft/webmagic/model/PageModelExtractor.java
index 043af10..522d491 100644
--- a/webmagic-extension/src/main/java/us/codecraft/webmagic/model/PageModelExtractor.java
+++ b/webmagic-extension/src/main/java/us/codecraft/webmagic/model/PageModelExtractor.java
@@ -15,11 +15,10 @@ import java.util.List;
 import java.util.regex.Pattern;
 
 /**
- * Model主要逻辑类。将一个带注解的POJO转换为一个PageModelExtractor。<br>
+ * The main internal logic of page model extractor.
  *
  * @author code4crafter@gmail.com <br>
- * Date: 13-8-1 <br>
- * Time: 下午9:33 <br>
+ * @since 0.2.0
  */
 class PageModelExtractor {
 
diff --git a/webmagic-extension/src/main/java/us/codecraft/webmagic/model/PageModelPipeline.java b/webmagic-extension/src/main/java/us/codecraft/webmagic/model/PageModelPipeline.java
index a70137f..2cb3808 100644
--- a/webmagic-extension/src/main/java/us/codecraft/webmagic/model/PageModelPipeline.java
+++ b/webmagic-extension/src/main/java/us/codecraft/webmagic/model/PageModelPipeline.java
@@ -3,9 +3,10 @@ package us.codecraft.webmagic.model;
 import us.codecraft.webmagic.Task;
 
 /**
+ * Implements PageModelPipeline to persistent your page model.
+ *
  * @author code4crafter@gmail.com <br>
- * Date: 13-8-3 <br>
- * Time: 上午9:34 <br>
+ * @since 0.2.0
  */
 public interface PageModelPipeline<T> {
 
diff --git a/webmagic-extension/src/main/java/us/codecraft/webmagic/model/annotation/package.html b/webmagic-extension/src/main/java/us/codecraft/webmagic/model/annotation/package.html
index 4e213f7..fbac5e9 100644
--- a/webmagic-extension/src/main/java/us/codecraft/webmagic/model/annotation/package.html
+++ b/webmagic-extension/src/main/java/us/codecraft/webmagic/model/annotation/package.html
@@ -1,5 +1,5 @@
 <html>
 	<body>
-Annotations for define a class.
+Annotations for defining a extractor.
 	</body>
 </html>
diff --git a/webmagic-extension/src/main/java/us/codecraft/webmagic/selector/JsonPathSelector.java b/webmagic-extension/src/main/java/us/codecraft/webmagic/selector/JsonPathSelector.java
index 5a41c47..2270384 100644
--- a/webmagic-extension/src/main/java/us/codecraft/webmagic/selector/JsonPathSelector.java
+++ b/webmagic-extension/src/main/java/us/codecraft/webmagic/selector/JsonPathSelector.java
@@ -6,8 +6,11 @@ import java.util.ArrayList;
 import java.util.List;
 
 /**
- * JsonPath
+ * JsonPath selector.<br>
+ * Used to extract content from JSON.<br>
+ *
  * @author code4crafter@gmail.com <br>
+ * @since 0.2.1
  */
 public class JsonPathSelector implements Selector {
 
@@ -43,7 +46,7 @@ public class JsonPathSelector implements Selector {
             return list;
         }
         if (object instanceof List) {
-            return (List<String>)object;
+            return (List<String>) object;
         } else {
             list.add(object.toString());
         }