HSKReadyGet the appHSK 3 Grammar: Expressing "Before" and "After" with （在）……以前/以后/前/后
In Mandarin Chinese, the frame （在）……以前/以后/前/后 places a reference time, action, or event inside the frame so that the temporal marker comes at the end of the phrase, opposite to English word order.
在吃饭以前，请先洗手。
Uses the full frame 在……以前 with a verb-object phrase (吃饭) in the slot.
× 以前吃饭，请先洗手。
Incorrect in this context: placing 以前 before 吃饭 follows English word order rather than the Chinese frame; 以前吃饭 would mean "when eating in the past". Use 在吃饭以前，请先洗手 instead.
Corrected example: 在吃饭以前，请先洗手。
Read the full explanation and examples
1. Core Concept and Word Order
In the HSK 3 syllabus, the fixed pattern （在）……以前/以后/前/后 is classified under fixed frames used to anchor an action in time relative to another point or event. For English speakers, the most important feature of this structure is its right-headed word order: whereas English puts "before" or "after" at the start of the time phrase (e.g., "before dinner"), Chinese places the reference point first and closes the frame with 以前, 前, 以后, or 后.
在 can introduce the time expression, while 以前 / 前 or 以后 / 后 follows the reference point. When the resulting phrase functions as a time adverbial, it normally comes before the main predicate, either before or after the subject. Other sentence patterns can use the whole phrase differently.
在吃饭以前，请先洗手。
Uses the full frame 在……以前 with a verb-object phrase (吃饭) in the slot.
你到了北京以后，给我打个电话。
Omits 在 and places a full clause (你到了北京) before 以后.
2. What Fills the Middle Slot?
The middle slot (reference-event-or-time) is highly flexible at the HSK 3 level. You can fill it with three main types of expressions:
- Specific points in time or dates: clock times (五点, five o'clock), days of the week (星期五, Friday), or calendar milestones.
- Verb phrases or short subject-verb clauses: actions like 吃饭 (eating a meal), 毕业 (graduating), or 你到了北京 (you arrive in Beijing).
- Time durations: quantities of time such as 三天 (three days) or 两年 (two years), which shift the translation to "...ago" or "...later".
我今天五点前能回家。
Omits 在 and uses the compact single-syllable 前 after a clock time (五点).
三天以后我们再讨论这个问题。
Fills the slot with a duration (三天) and omits 在.
3. Comparing the Subforms: 在, 以前/以后, and 前/后
Because the outline groups （在）, 以前/以后, and 前/后 together, learners need clear guidelines on how to choose among them in real communication.
- 在 is often omitted, especially in concise time phrases, but a duration does not make it ungrammatical: 我是在三天以后才收到信的 emphasizes when the letter arrived. A clause can also follow 在, even when its subject refers to the same person as the main subject: 在我毕业以后，我去了上海. Read the two clauses separately to identify who does each action.
- 以前 / 以后 versus 前 / 后: In most framed contexts, the two-syllable words 以前 and 以后 are interchangeable with the single-syllable words 前 and 后. The two-syllable forms sound slightly more conversational and natural in spoken Mandarin, whereas single-syllable 前 and 后 are more compact and frequent in written Chinese or fixed expressions (such as 五点前 or 毕业后).
- Rhythm and established combinations matter more than simply counting syllables. 睡前 (“before sleeping”) and 用前 (“before use”) are natural single-verb combinations. If a shorter form is awkward in your sentence, use 以前 / 以后 or a fuller action phrase instead.
在大学毕业后，他去上海工作了。
Combines 在 with the compact single-syllable 后 in a slightly more formal narrative sentence.
4. Crucial Contrast: Framed vs. Standalone Usage
A common mistake occurs when learners translate English "before eating" word-for-word by putting 以前 in front of the verb. If 以前 or 以后 appears before a verb or subject without a preceding reference point, it does not mean "before doing X" or "after doing X". Instead, it functions as a standalone time word meaning "in the past / previously" (以前) or "in the future / from now on" (以后).
× 以前吃饭，请先洗手。
Incorrect in this context: placing 以前 before 吃饭 follows English word order rather than the Chinese frame; 以前吃饭 would mean "when eating in the past". Use 在吃饭以前，请先洗手 instead.
Corrected example: 在吃饭以前，请先洗手。
以前我不喜欢喝咖啡，现在每天都喝。
Correct standalone use of 以前 meaning "previously / in the past", contrasting with the framed structure.
Frequently asked questions
Can I always add 在 in front of a ……以前 or ……以后 phrase?
在 is often optional before a time reference or action clause. Omission is common in 三天以后, but 在三天以后 is possible when the surrounding sentence naturally emphasizes that time, for example 我是在三天以后才收到信的. A duration alone is not a reason to mark 在 as wrong.
Is there any difference in meaning between 以前/以后 and 前/后 inside this frame?
The forms often express the same before/after relation, with different rhythm and conventional combinations. Exact time interpretation still depends on context: a phrase can locate a point or describe a broader earlier/later period. Do not assume the longer form always specifies exactly the same single instant.
Can I use 了 inside the （在）……以后 frame?
Yes. When the middle slot describes an action that must be completed before the next action happens (such as 到了北京以后, "after arriving in Beijing"), adding 了 after the verb inside the frame is very natural.
