Undocumented
a. 无正式文件的, 无事实证明的
🗣️ 情景例句
That sounds a good idea. Thank you.
好主意！谢谢你。
What month is this?
现在是几月份？
I'd like to take a boat on the River Nile.
我想乘船在尼罗河上游览。