1. (文章等)传递，传阅，散发
    If a piece of writing circulates or is circulated, copies of it are passed round among a group of people.

    e.g. The document was previously circulated in New York at the United Nations...
           这份文件先前在纽约的联合国总部传阅过。
    e.g. Public employees, teachers and liberals are circulating a petition for his recall...
           公务员、教师和自由派人士正在散发请愿书，要求将他召回。

2. (谣言等)流传;散布
    If something such as a rumour circulates or is circulated, the people in a place tell it to each other.

    e.g. Rumours were already beginning to circulate that the project might have to be abandoned...
           已传出谣言说，该项目可能会被迫取消。
    e.g. I deeply resented those sort of rumours being circulated at a time of deeply personal grief.
           我特别憎恨那种在人家伤心透顶的时候还在传播的谣言。

3. (在密闭场所或系统内)循环，流转，传播
    When something circulates, it moves easily and freely within a closed place or system.

    e.g. ...a virus which circulates via the bloodstream and causes ill health in a variety of organs...
           通过血液循环传播、造成多种器官病变的病毒
    e.g. Cooking odors can circulate throughout the entire house.
           做饭的香味可以传到家里的各个角落。

4. (在聚会上)周旋，往来应酬
    If you circulate at a party, you move among the guests and talk to different people.

circulate的意思

    e.g. Let me get you something to drink, then I must circulate.
           我给你找点喝的，然后我得去应酬一下。