diff --git a/README_EN.md b/README_EN.md
index d47aa68..748cb84 100644
--- a/README_EN.md
+++ b/README_EN.md
@@ -32,6 +32,8 @@ Edit `src/lib.rs` to implement `collection` function
 ```rust
 source: &str, // source text
 target: &str, // target text
+from: &str, // source language code
+to: &str, // target language code
 needs: HashMap<String, String>, // Additional configuration information required by the plugin, defined by info.json
 ```