twice的詞性和用法

　　例句：

　　1、We go there maybe once or twice a month.

　　我們每月大概去那里一到兩次。

　　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。

　　4、You should think twice about employing someone you've never met.

　　雇用素不相識的人應三思而行。