twice什麼詞性

twice，主要用作為副詞，例如：

1、We go there maybe once or twice a month.我們每月大概去那裡一到兩次。

2、You should visit your dentist at least twice a year.你應該每年至少去看兩次牙科醫生。

3、New drivers have twice as many accidents as experienced drivers.新駕駛員所出的事故是老駕駛員的兩倍。