per/pə(r)/
prep.1. （数量、价格等）每one apple per child每个孩子一个苹果
The fruit costs 30 pence per kilo.水果每公斤30便士。
2. （时间）每一40 words per minute每分钟40个单词
How much do you earn per week?你每周挣多少钱？
My rent is $8000 per annum.我的房租是每年六千美元。
3. 按照The work has been done as per instructions.工作已按照指示做完。