if a type of medicine is available over the counter, you can buy it without the permission of a doctor.
You can't buy antibiotics over the counter - they're a prescription drug.
英语词组固定搭配大全包含18674条英汉双解词组，基本涵盖了全部常用英文词组、短语的翻译及用法，是英语学习的有利工具。