bi-
pref 前缀 two; twice 二; 两次: biannual
bicentenary. Cf 参看 di-, tri-. bi-, NOTE ON USAGE 用法
Note that bi- is used with certain expressions of time (eg bimonthly) to mean both `every two´ (months) and `twice a´ (month) 注意bi-附加在某些表示时间的词语前面(如 bimonthly), 兼有`每两'(月)和(每月)`两次'两种含义. There is a distinction between biennial (every two years) and biannual (twice a year). *biennial意为`每两年', biannual意为`每年两次', 这二者的区别则十分清楚.