diff --git a/docs-2.0-zh/3.ngql-guide/5.operators/1.comparison.md b/docs-2.0-zh/3.ngql-guide/5.operators/1.comparison.md
index 955f0531c34..7cab419986f 100644
--- a/docs-2.0-zh/3.ngql-guide/5.operators/1.comparison.md
+++ b/docs-2.0-zh/3.ngql-guide/5.operators/1.comparison.md
@@ -119,6 +119,7 @@ nebula> YIELD 1 != '1';
 ### `IS [NOT] NULL`
 
 ```ngql
+# 返回关于 null 的一些判断结果。
 nebula> RETURN null IS NULL AS value1, null == null AS value2, null != null AS value3;
 +--------+----------+----------+
 | value1 | value2   | value3   |
@@ -126,6 +127,7 @@ nebula> RETURN null IS NULL AS value1, null == null AS value2, null != null AS v
 | true   | __NULL__ | __NULL__ |
 +--------+----------+----------+
 
+# 返回关于 NULL 的一些属性信息。
 nebula> RETURN length(NULL), size(NULL), count(NULL), NULL IS NULL, NULL IS NOT NULL, sin(NULL), NULL + NULL, [1, NULL] IS NULL;
 +--------------+------------+-------------+--------------+------------------+-----------+-------------+------------------+
 | length(NULL) | size(NULL) | count(NULL) | NULL IS NULL | NULL IS NOT NULL | sin(NULL) | (NULL+NULL) | [1,NULL] IS NULL |
@@ -133,6 +135,7 @@ nebula> RETURN length(NULL), size(NULL), count(NULL), NULL IS NULL, NULL IS NOT
 | __NULL__     | __NULL__   | 0           | true         | false            | __NULL__  | __NULL__    | false            |
 +--------------+------------+-------------+--------------+------------------+-----------+-------------+------------------+
 
+# 创建 map 数据，判断 map 的 name 属性是否不为 NULL。
 nebula> WITH {name: null} AS `map` \
         RETURN `map`.name IS NOT NULL;
 +----------------------+
@@ -141,6 +144,7 @@ nebula> WITH {name: null} AS `map` \
 | false                |
 +----------------------+
 
+# 创建 map1、map2、map3 的数据，并判断返回其 name 属性是否为 NULL。
 nebula> WITH {name: 'Mats', name2: 'Pontus'} AS map1, \
         {name: null} AS map2, {notName: 0, notName2: null } AS map3 \
         RETURN map1.name IS NULL, map2.name IS NOT NULL, map3.name IS NULL;
@@ -150,6 +154,7 @@ nebula> WITH {name: 'Mats', name2: 'Pontus'} AS map1, \
 | false             | false                 | true              |
 +-------------------+-----------------------+-------------------+
 
+# 查询所有 Tag 为 player 的点数据，判断并返回点的 age 属性是否为 NULL、name 属性是否不为 NULL、empty 属性是否为 NULL。
 nebula> MATCH (n:player) \
         RETURN n.player.age IS NULL, n.player.name IS NOT NULL, n.player.empty IS NULL;
 +----------------------+---------------------------+------------------------+
@@ -163,6 +168,7 @@ nebula> MATCH (n:player) \
 ### `IS [NOT] EMPTY`
 
 ```ngql
+# 判断 null 是否不存在。
 nebula> RETURN null IS EMPTY;
 +---------------+
 | NULL IS EMPTY |
@@ -170,6 +176,7 @@ nebula> RETURN null IS EMPTY;
 | false         |
 +---------------+
 
+# 判断 a 字符串是否存在。
 nebula> RETURN "a" IS NOT EMPTY;
 +------------------+
 | "a" IS NOT EMPTY |
@@ -177,6 +184,7 @@ nebula> RETURN "a" IS NOT EMPTY;
 | true             |
 +------------------+
 
+# 遍历所有 player100 指向的目的点，并返回目的点数据 name 属性存在的点 id。
 nebula> GO FROM "player100" OVER * WHERE properties($$).name IS NOT EMPTY YIELD dst(edge);
 +-------------+
 | dst(EDGE)   |