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Co-authored-by: TomShawn <41534398+TomShawn@users.noreply.github.com>

choose-index.md

@@ -35,7 +35,7 @@ TiDB selects indexes based on rules or cost. The based rules include pre-rules a
 
 #### Pre-rules
 
-TiDB uses the following heuristic pre rules to select indexes:
+TiDB uses the following heuristic pre-rules to select indexes:
 
 + Rule 1: If an index satisfies "unique index with full match + no need to retrieve rows from a table (which means that the plan generated by the index is the IndexReader operator)", TiDB directly selects this index.
 
@@ -105,7 +105,7 @@ mysql> SHOW WARNINGS;
 1 row in set (0.00 sec)
 ```
 
-### Selection based on cost estimation
+### Cost estimation-based selection
 
 After using the skyline-pruning rule to rule out inappropriate indexes, the selection of indexes is based entirely on the cost estimation. The cost estimation of accessing tables requires the following considerations: