Undocumented
a. 无正式文件的, 无事实证明的
🗣️ 情景例句
I have been a poor student of foreign languages.
外语就学得不好。
A burnt child dreads the fire.
一朝被蛇咬，十年怕井绳。
The situation seemed hopeless and he knew his life was in danger.
这种情况看来是毫无希望了，他知道他有生命危险。