twice 
英 [twaɪs]  美 [twaɪs] 
adv. 两次；两倍

例句：
Try to do this exercise at least twice a week. 

争取每天做两次这种运动。

This famous horse race has taken place here twice a year since 1310. 

自1310年以来，这项知名的赛马比赛每年在这里举行两次。

Foster, who is twice the world champion, competes today. 

两届世界福斯特也参加了今天的比赛。

The figure of seventy-million pounds was twice as big as expected. 

7,000万英镑的数额是预期的两倍。

It took us nearly twice as long to return to the station. 

返回车站花了我们将近两倍的时间。

She should think twice before saying such stupid things. 

她在说这些蠢话之前应该先在脑子里过两遍。