之
Explanation
"之"作为结构助词，用于连接定语和中心语，表示修饰或所属关系，相当于现代汉语的"的"，多用于书面语和正式表达中。
"之" functions as a structural particle that connects a modifier to a head noun, indicating possession or modification, equivalent to the modern Chinese particle "的", and is primarily used in written and formal contexts.
Examples
我们可以将北京描绘为一本梦之书。
We can depict Beijing as a book of dreams.
由于做了好事，做出了贡献，因此他得到所爱之人的欣赏。
Because he did good deeds and made contributions, he gained the appreciation of the person he loved.
Related Grammar Points
而已HSK 7七—九057
词类 · 语气助词
用于句末，表示事情仅仅如此，程度或数量不大，带有轻描淡写的语气。
Used at the end of a sentence to indicate that something is merely so, with a tone of downplaying its significance or extent.
Examples (2)
这算什么，只是一堆纸而已。
What’s this supposed to be? Just a pile of papers, that’s all.
我不过是出于好奇，随便问问而已。
I was just curious, asking casually, that’s all.
矣HSK 7七—九058
词类 · 语气助词
语气助词“矣”用于句末，表示事情已经完成、实现，或表示感叹、肯定的语气，相当于现代汉语的“了”、“啦”。
The particle '矣' (yǐ) is used at the end of a sentence in classical or formal Chinese to indicate completion, realization, or to express a tone of exclamation or affirmation, equivalent to '了' (le) or '啦' (la) in modern Chinese.
Examples (2)
人生得一知己足矣。
In life, having one true friend is enough.
他的想法可谓多矣。
His ideas can be said to be numerous.