In short

Formal written Chinese (书面语体) is the same grammar made denser: everyday two-syllable words shrink to single classical characters. Master four borrowed function words - 于 (yú, ≈ 在/比/给), 之 (zhī, ≈ 的/it), 而 (ér, links predicates), 以 (yǐ, ≈ 用/为了) - plus the suffixes 化 (“-ize”) and 性 (“-ness”) and four-character idioms 四字格. Reach for them in essays, news and documents; keep them out of casual speech.

The rule

书面语体 (shūmiànyǔtǐ, “written register”) is the Chinese of essays, news reports, contracts and formal speeches. It is not a different grammar - it is ordinary grammar made classical and compact: colloquial words contract to single characters, and a handful of borrowed function words do the work that particles and prepositions do in speech. The contraction reaches the question too: a written yes-no question does not tag 吗 on the end but squeezes spoken 是不是 / 能不能 into 是否 (shìfǒu) and 能否 (néngfǒu) - 是否需要预约？ (shìfǒu xūyào yùyuē, “is a booking required?”), 能否按时完成？ (néngfǒu ànshí wánchéng, “can it be finished on time?”).

Step 1 - 于 (yú): the all-purpose classical preposition. 于 attaches to a verb or adjective - usually after it - and covers several spoken prepositions at once:

• place / time (= 在): 位于 (wèiyú, “be located at”), 生于1990年 (shēng yú yī jiǔ jiǔ líng nián, “born in 1990”).
• comparison (= 比): after an adjective - 大于 (dàyú, “greater than”), 优于 (yōuyú, “superior to”).
• target / benefit (= 对/给): 有利于 (yǒulì yú, “beneficial to”), 致力于 (zhìlì yú, “devote oneself to”).

Unlike spoken 在, which sits before the verb, 于 usually rides behind it and fuses into a fixed compound (位于、属于、源于). A place or time 于-phrase may stand in front of the verb instead - 本次会议于北京举行, 工程将于下月完工 - but either way 于 leans on a verb or adjective; what it never does is stand before a bare noun with no predicate at all.

Step 2 - 之 (zhī): classical 的 and classical “it”. Two jobs:

• attributive (= 的): survives in set phrases - 无价之宝 (wújià zhī bǎo, “a priceless treasure”), 意料之中 (yìliào zhī zhōng, “as expected”). It also pairs with a localizer to build written place/time words: 之后、之前、之间、之中、之一 (“after, before, between, among, one of”).
• object pronoun (= 它/them), pointing back at something just mentioned: 取而代之 (qǔ ér dài zhī, “replace it”), 反之 (fǎnzhī, “conversely”).

You cannot use 之 as a free “的” for ordinary possession - say 我的书, never 我之书.

Step 3 - 而 (ér): the predicate connector. 而 joins two predicates (verbs or adjectives), never two nouns. It signals how the second follows from the first - sequence, manner, purpose or contrast:

V1 / Adj1 + 而 + V2 / Adj2

起身而去 (qǐshēn ér qù, “get up and leave”), 华而不实 (huá ér bù shí, “flashy but hollow”). Its contrastive “whereas” sense and the 为……而 purpose frame are handled in Contrast connectives and Purpose clauses; here the point is that 而 is the glue of formal predicates. For “and” between nouns, still use 和/跟.

Step 4 - 以 (yǐ): “by means of” and “so as to”. Two core senses:

• instrument / basis (= 用/根据): the frame 以 X 为 Y (“take X as Y”) is everywhere - 以事实为依据 (yǐ shìshí wéi yījù, “take facts as the basis”), 以……为主 (“with X as the main part”), 以身作则 (“lead by example”).
• purpose (= 为了): a bare 以 + Verb tail meaning “so as to” - 以示公平 (yǐ shì gōngpíng, “so as to show fairness”), 以求进步 (yǐ qiú jìnbù, “in order to seek progress”).

以 also builds written range words: 以上、以下、以内、以来 (“above, below, within, since”).

Step 5 - the suffix 化 (huà): “-ize / -ification”. Attach 化 to a noun or adjective to make a verb or process noun meaning “become / make X”: 现代 -> 现代化 (xiàndàihuà, “modernize / modernization”), 全球 -> 全球化 (“globalization”), 简 -> 简化 (“simplify”), 恶 -> 恶化 (“worsen”). It can take an object (美化环境, “beautify the environment”) or stand alone (情况恶化了, “the situation worsened”).

Step 6 - the suffix 性 (xìng): “-ness / -ity”. Attach 性 to make an abstract noun naming a property: 可能 -> 可能性 (kěnéngxìng, “possibility”), 重要 -> 重要性 (“importance”), 安全 -> 安全性 (“safety”). The result is a noun, so it takes 的 and measure words, not the degree adverb 很 - say 问题的重要性, never 很重要性.

Step 7 - 四字格 (sìzìgé): four-character set expressions. Formal Chinese loves four-beat idioms that compress a whole clause into four syllables, often built on these very function words: 显而易见 (xiǎn ér yì jiàn, “obviously”), 持之以恒 (chí zhī yǐ héng, “persevere steadily”). Learn each as one lexical unit - do not translate it character by character.

Forms & patterns

The core toolkit at a glance:

The many senses of 于 (attached to a verb or adjective, usually after it):

The two productive suffixes - same root, different part of speech:

A few high-frequency 四字格 (several hide these function words inside):

Examples

Common mistakes

• 我之书 -> 我的书 (wǒ de shū) - 之 keeps its “的” sense only inside fixed literary phrases (无价之宝、意料之中); ordinary possession is plain 的.
• 我而你都同意。 -> 我和你都同意。 (Wǒ hé nǐ dōu tóngyì.) - 而 links predicates or clauses, never two nouns; “and” between nouns is 和/跟.
• 这个问题很严重性。 -> 这个问题很严重。 (Zhège wèntí hěn yánzhòng.) - 性 builds an abstract noun, which cannot follow 很; use the bare adjective, or make a noun phrase 问题的严重性.
• 以事实依据 -> 以事实为依据 (yǐ shìshí wéi yījù) - the frame is 以 X 为 Y; you cannot drop the 为.
• 这本书于桌子上。 -> 这本书在桌子上。 (Zhè běn shū zài zhuōzi shàng.) - free-standing spoken “at” is 在; 于 is bookish and normally fuses onto a verb (位于、置于), not left before a bare noun.

Tips

• Register switch, one for one: spoken 在 / 的 / 用 become written 于 / 之 / 以; spoken 他的 / 它的 becomes 其 (qí), which sits straight in front of its noun and never takes 的 (它的名称 -> 其名称); spoken 会 / 要 becomes 将 (jiāng) - 工程将于下月完工 (gōngchéng jiāng yú xià yuè wángōng, “the works will be finished next month”); and spoken 就 becomes 便 or 即 (biàn / jí) - 缴费后即可入场 (jiǎofèi hòu jí kě rùchǎng, “once you have paid you may go in”). A two-syllable verb often shrinks to one character as well. If a sentence sounds like a news anchor, these words fit; if it sounds like a text to a friend, drop them.
• 于 pronunciation and habit: 于 is yú (2nd tone) and almost never stands alone - learn the whole V+于 word (位于、属于、在于、致力于). It usually follows its verb, where spoken 在 precedes it - but a place or time 于-phrase may sit in front of the verb too (于北京举行).
• 化 vs 性, same root, different job: 化 makes a verb of change (“-ize”), 性 makes a noun of property (“-ness”). 现代化 = “to modernize”, 现代性 = “modernity”; 可能 = “possible”, 可能性 = “possibility”.
• 四字格 are whole words: store them as single chunks and never parse them literally - 显而易见 is “obviously”, not “clear-and-easy-see”. Note the tone sandhi in 一举两得: 一 shifts to 4th tone (yì jǔ liǎng dé) before the 3rd-tone 举.