当表扬一个英文小天才时，可以使用以下礼貌用语：

1. "You are incredibly talented in English!"

3. "You have a remarkable command of the English language!"

4. "Your English skills are outstanding!"

6. "I'm amazed by your English abilities!"

7. "You excel in English like no other!"

8. "Your English proficiency is top-notch!"