资料来源 : pyDict

二年一次地,每两年

资料来源 : Webster's Revised Unabridged Dictionary (1913)

Biennially \Bi*en"ni*al*ly\, adv.
   Once in two years.

资料来源 : WordNet®

biennially
     adv : every two years; "this festival takes places biennially"
           [syn: {biyearly}]