---There’s a ___on his face.---You don't know?He comes first in his test.

问题描述:

---There’s a ___on his face.---You don't know?He comes first in his test.
根据对话内容,写出句中所缺单词的正确形式、、每空一词~

smile
他脸上面带微笑.
加油!