Update README.md

README.md

@@ -19,7 +19,7 @@ This dataset is collected from real middle school exams in China, and all the ma
 The MM_math description contains two documents:
 
 1. **image.tar**: This archive includes images used in the problems.
-2. **MM_Math.json**: This file contains collected middle school exam questions, including the problem statement, solution process, and 3D annotations.
+2. **MM_Math.json**: This file contains collected middle school exam questions, including the problem statement, solution process, and 3 dimension annotations.
 
 
 ##  Data Format