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Using the Preposition 于 (yú) to Introduce Time and Location
In formal and written Mandarin, the preposition 于 (yú) introduces points in time, locations, and origins both before and after the main verb.
该协议于去年十月正式生效。
Pre-verbal 于 introduces a specific time in an official announcement.
× 他出生了于上海。
Incorrect: The aspect particle 了 cannot be inserted between the verb 出生 and the post-verbal preposition 于. Replace with 他出生于上海。
Corrected example: 他出生于上海。
Read the full explanation and examples
Core Function and Register
The HSK 6 outline lists 于 (yú) here as introducing time and place. This lesson also contrasts related source expressions such as 源于. 于 has other uses elsewhere, so these examples are not an exhaustive definition of the word.
Unlike everyday spoken prepositions, 于 belongs solidly to written and formal spoken registers. You will encounter it frequently in news broadcasts, historical summaries, biographical notes, academic writing, and official notices. Depending on the sentence pattern and the verb involved, a prepositional phrase led by 于 can stand either before the main verb phrase as an adverbial modifier or immediately after the verb as a complement.
Pre-Verbal Structure: Setting the Scene
Before the main verb phrase, 于 can introduce a time or place, as in 于去年十月正式生效 and 于北京举行会谈. This gives a formal style. A time or place need not be a proper name: the phrase supplies the setting for the following event.
该协议于去年十月正式生效。
Pre-verbal 于 introduces a specific time in an official announcement.
双方代表于北京举行了会谈。
于北京 locates the talks in Beijing, before the verb phrase 举行了会谈. Notice that 了 stays within the following verb phrase.
Post-Verbal Structure: Complements of Time, Place, and Origin
In combinations such as 生于, 建于, 始于 and 源于, 于 follows the verb and introduces a time, place or source. Longer combinations include 出生于 and 毕业于. Learn each pairing as a whole rather than moving 于 to either side of any verb. A source phrase such as 源于一份报告 is not the location where a report was written.
这座古桥建于明代。
Post-verbal 于 attaches directly to 建 to introduce the historical period.
那位作家生于江南的一个小镇。
Post-verbal 于 introduces a birthplace in biographical prose.
这条消息源于一份内部报告。
Post-verbal 于 after 源 introduces the source or origin.
Contrasting 于 with 在 and 从
Because 于 covers meanings expressed by 在 (at, in, on) and 从 (from) in everyday speech, choosing between them depends on register, sentence position, and collocation:
- Register: 在 and 从 fit ordinary conversation and standard writing. 于 often gives a more formal tone in these patterns. 我在家吃午饭 is the ordinary conversational choice; a sentence with 于 may be intentionally literary or formal rather than ungrammatical merely because it is spoken.
- Post-verbal time phrases: 建于明代 and 写于1990年 are established formal patterns. 在 can also introduce a time after suitable verbs, as in 生在春天. Do not choose solely by “time versus place”: the verb, event meaning and register determine which whole expression fits.
- Starting points and origins: compare 从唐代开始 with 始于唐代, and 从生活中取材 with 取材于生活. The constructions package the source or starting point differently. Changing the preposition may require changing the verb phrase or its position; it is not a one-character substitution.
Common Learner Mistake and Limits
In the intended biographical statement 他出生于上海, keep 出生于 together; 他出生了于上海 is not the standard form. Removing the inserted 了 repairs this sentence without changing its meaning. Do not infer that all 于 sentences describe completed past events: 将于明天举行 is future, and source expressions can describe a continuing relationship.
× 他出生了于上海。
Incorrect: The aspect particle 了 cannot be inserted between the verb 出生 and the post-verbal preposition 于. Replace with 他出生于上海。
Corrected example: 他出生于上海。
他出生于上海。
Correct replacement: The verb 出生 connects directly to 于 without an aspect marker.
Frequently asked questions
Can I replace 在 with 于 in everyday conversation?
Usually keep 在 in an ordinary conversational expression such as 我在家吃饭. 于 sounds more formal and depends on the verb and construction. A spoken sentence can intentionally use that register, but 于 is not a general replacement for 在 in every position.
Does 于 only introduce time and location?
In this specific HSK 6 grammar item, the focus is on introducing time, location, and origin. However, in broader Chinese grammar, 于 can also introduce targets, recipients, or standards of comparison in other patterns.
Can 了 ever appear in a sentence with 于?
Yes, when 于 + time/place appears before the verb, the main verb that follows can take 了 (as in 于北京举行了会谈). However, when 于 appears immediately after the verb as a complement, 了 cannot be placed between the verb and 于.
