Update 5.zone.md (#849)

docs-2.0/7.data-security/5.zone.md

@@ -4,33 +4,33 @@ The Group&Zone feature groups the nodes where Storage services are located (also
 
 ## Background
 
-Storage nodes can be added to a Zone, and multiple Zones form a Group. If you specify a Group when creating a space, the space will be created and stored on the Storage nodes within the Group. Data partitions and replicas are stored evenly in each Zone as shown below.
+Storage nodes can be added into a Zone, and multiple Zones form a Group. If you specify a Group when creating a space, the space will be created and stored on the Storage nodes within the Group. Data partitions and replicas are stored evenly in each Zone as shown below.
 
 ![Group&Zone sketch map](zone1.png)
 
-Suppose that 8 Storage nodes are divided into 4 Zones, with each one having 2 Storage nodes, and then add Zone1, Zone2, and Zone3 to Group1，add Zone3, Zone4 to Group2.
+Suppose that 8 Storage nodes are divided into 4 Zones, with each one having 2 Storage nodes, and then add Zone1, Zone2, and Zone3 into Group1, add Zone3 and Zone4 into Group2.
 
 After specifying Group1 when you create a space called S1, data partitions and replicas will be stored evenly on the nodes in Zone1, Zone2, and Zone3, and will not be stored on the node in Zone4.
 
 After specifying Group2 when you create another space called S2, data partitions and replicas will be stored evenly on the nodes in Zone3 and Zone4, and will not be stored on the nodes in Zone1 and Zone2.
 
-The above example briefly introduces the Zone feature. Resources are isolated by rational planning of Zones and Groups.
+The above example briefly introduces the zone feature. Users can isolate resources by balanced planning of Zones and Groups.
 
-## Scenario
+## Scenarios
 
 - Create a space on specified Storage nodes to isolate resources.
 
-- Perform rolling upgrade of a cluster in which you need to stop one or more nodes before the cluster is upgraded, and then restart the nodes until all services on the nodes in the cluster are updated to the latest version.
+- Perform rolling upgrade of a cluster which requires stopping one or more nodes before the cluster is upgraded, and then restart the nodes until all services on the nodes in the cluster are updated to the latest version.
 
-## Note
+## Precautions
 
-- A Zone is a collection of Storage nodes, and each Storage node can only be added to one Zone.
+- A Zone is a collection of Storage nodes, and each Storage node can only be added into one Zone.
 
 - Replicas can be restored in a Zone, and only one replica of the same partition can exist in a Zone.
 
-- Many Zones form a Group where resources are isolated.
+- Many Zones can form a Group for easy management and resource isolation.
 
-- A Zone can be added to multiple Groups.
+- A Zone can be added into multiple Groups.
 
 - If you specify a Group when creating a space, replicas in the space will be distributed evenly in each Zone within the Group.
 
@@ -40,7 +40,7 @@ The above example briefly introduces the Zone feature. Resources are isolated by
 
 ### ADD ZONE
 
-Create a Zone and add Storage nodes to the Zone.
+Create a Zone and add Storage nodes into the Zone.
 
 ```ngql
 ADD ZONE <zone_name> <host1>:<port1> [,<host2>:<port2>...];
@@ -54,11 +54,11 @@ nebula> ADD ZONE zone1 192.168.8.111:9779, 192.168.8.129:9779;
 
 ### ADD HOST...INTO ZONE
 
-Add a Storage node to a created Zone.
+Add a Storage node into a created Zone.
 
 !!! note
 
-    Use the [BALANCE](../3.ngql-guide/18.operation-and-maintenance-statements/2.balance-syntax.md) command to perform loading balancing after the Storage node is added to a created Zone.
+    Use the [BALANCE](../3.ngql-guide/18.operation-and-maintenance-statements/2.balance-syntax.md) command to implement load balance after the Storage node is added into a created Zone.
 
 ```ngql
 ADD HOST <host1>:<port1> INTO ZONE <zone_name>;
@@ -70,15 +70,15 @@ Delete a Storage node from a Zone.
 
 !!! note
 
-    You cannot delete a Storage node that is being used in a Group. Delete the related space before the Storage node is deleted.
+    You cannot delete a Storage node that is being used in a Group directly until the related space is deleted.
 
 ```ngql
 DROP HOST <host1>:<port1> FROM ZONE <zone_name>;
 ```
 
 ### SHOW ZONES
 
-View all Zones
+View all Zones.
 
 ```ngql
 SHOW ZONES;
@@ -99,15 +99,15 @@ Delete a Zone.
 
 !!! note
 
-    You cannot delete a Zone that has been added to a Group. Remove the Zone from the Group or delete the Group before the Zone is deleted.
+    You cannot delete a Zone that has been added into a Group until the Zone is removed from the Group or the Group to which the Zone belongs is deleted.
 
 ```ngql
 DROP ZONE <zone_name>;
 ```
 
 ### ADD GROUP
 
-Create a Group and add one or more Zones to the Group.
+Create a Group and add one or more Zones into the Group.
 
 ```ngql
 ADD GROUP <group_name> <zone_name> [,<zone_name>...];
@@ -121,11 +121,11 @@ nebula> ADD GROUP group1 zone1,zone2;
 
 ### ADD ZONE...INTO GROUP
 
-Add a Zone to a created Group.
+Add a Zone into a created Group.
 
 !!! note
 
-    Use the [BALANCE](../3.ngql-guide/18.operation-and-maintenance-statements/2.balance-syntax.md) command to perform loading balancing after the Zone is added to a created Group.
+    Use the [BALANCE](../3.ngql-guide/18.operation-and-maintenance-statements/2.balance-syntax.md) command to implement load balance after the Zone is added into a created Group.
 
 ```ngql
 ADD ZONE <zone_name> INTO GROUP <group_name>;
@@ -137,7 +137,7 @@ Delete a Zone from a GROUP.
 
 !!! note
 
-    You cannot delete a Zone that is being used in a Group. Delete the related space before the Zone is deleted.
+    You cannot delete a Zone that is being used in a Group directly until the related space is deleted.
 
 ```ngql
 DROP ZONE <zone_name> FROM GROUP <group_name>;
@@ -166,7 +166,7 @@ Delete a Group.
 
 !!! note
 
-    You cannot delete a Group that is being used. Delete the related space before the Group is deleted.
+    You cannot delete a Group that is being used directly until the related space is deleted.
 
 ```ngql
 DROP GROUP <group_name>;