per

The preposition 'per' indicates rate, ratio, or distribution (for each); it expresses conformity with rules, instructions, or agreements ('according to'), denotes means or method ('by way of'), and appears in fixed Latin-derived expressions to specify units, standards, or formal references.

• 🇨🇳介词“per”表示按比例、比率或分配单位（每、每一）；也表示按照规则、指示或协议（按照、根据），还表示通过某种方式或方法（通过、经由），并常见于拉丁语源的固定表达中，用于指称单位、标准或正式引用。

1. Rate, ratio, or distribution (for each) B1 formal business

   Indicates a quantity, price, speed, or frequency relative to a single unit of measurement, person, or time period

   • The car consumes 6 liters per 100 km
   • Tickets cost $20 per person
   • She exercises three times per week

   🇨🇳每、按

2. According to / in accordance with B2 formal business

   Used to indicate that something is done in conformity with rules, instructions, agreements, or established procedures

   • Per your request, I've attached the report
   • The work was done per the contract
   • Per company policy, all emails are monitored

   🇨🇳按照；根据；依照

3. By means of / through (formal/archaic) C1 formal business

   Indicates the method, channel, or medium by which something is transmitted, delivered, or accomplished

   • Please send the documents per courier
   • The message was transmitted per radio
   • Payment can be made per bank transfer

   🇨🇳通过；经由

4. In fixed Latin expressions (per se, per capita, per annum) C1 formal legal

   Appears in established Latin-derived phrases used in formal, academic, legal, or business contexts to express specific concepts

   • The idea is not flawed per se
   • Income per capita has risen
   • The interest rate is 5% per annum

   🇨🇳每、按（拉丁固定短语）

5. Allocation or apportionment B2 formal business

   Used to specify how resources, duties, or quantities are distributed or assigned among units, groups, or categories

   • Each team receives two laptops per department
   • The budget allocates $500 per project
   • Rules apply per household, not per person

   🇨🇳每，按