Update 5.lookup.md

docs-2.0/3.ngql-guide/7.general-query-statements/5.lookup.md

@@ -16,7 +16,7 @@ This topic applies to native nGQL only.
 
 ## Precautions
 
-- Correct use of indexes can speed up queries, but indexes can dramatically reduce the write performance. The performance reduction can be as much as 90% or even more. **DO NOT** use indexes in production environments unless you are fully aware of their influences on your service.
+- Correct use of indexes can speed up queries, but indexes can dramatically reduce the write performance. The performance reduction can be 90% or even more. **DO NOT** use indexes in production environments unless you are fully aware of their influences on your service.
 
 - If the specified property is not indexed when using the `LOOKUP` statement, Nebula Graph randomly selects one of the available indexes.
 
@@ -28,7 +28,7 @@ This topic applies to native nGQL only.
 
 ## Prerequisites
 
-Before using the `LOOKUP` statement, make sure that at least one index is created. If there are already related vertices, edges, or properties before an index is created, the user must [rebuild native index](../14.native-index-statements/4.rebuild-native-index.md) after creating the index to make it valid.
+Before using the `LOOKUP` statement, make sure that at least one index is created. If there are already related vertices, edges, or properties before an index is created, the user must [rebuild the index](../14.native-index-statements/4.rebuild-native-index.md) after creating the index to make it valid.
 
 ## Syntax