图书流通率的英文：
annual circulation
adj. 每年的，年度的；年生的
n. 年刊，年报，年鉴；年生植物
multiple (double) annual ring
复年轮
annual ring density
年轮密度
He endows this university annually.
他每年都会资助这所大学。
Companies report to their shareholders annually.
各公司每年向其股东汇报一次。
The Association holds an annual reunion.
这个协会每年聚会一次。
n. 血液循环；流通，传播；发行量
Have you been circulated with details of the conference?
你收到会议详情的通知了吗？
circulate counterfeit coins
使伪造的钱币流通
This magazine has a large circulation.
这本杂志发行量很大。
The circulation of gossip is abhorrent.
传播流言蜚语是可恶的。
The air was circulated mechanically.
空气循环是靠机械驱动的。