Part 1 字首 表示{数字}的字首 du- = two 二
入门字
double (n.) 两倍 (v.) 增加一倍 (a.) 双重的
dou/ ble
two/ fold
进阶字
1. dual (a.) 双重的
du/ al
two/ 形容词字尾
TIME Express serves the dual purpose of supplying information and aiding language acquistion.
《解读时代》负有双重使命：提供资讯以及辅助语言学习。
2. duet (n.) 二重奏，二重唱
du/ et
two/ 名词字尾
A duet requires two players or singers to perform.
二重奏（二重唱）要有两个乐手或歌手演出。
3. duplicity (n.) 诈欺，两面手法
du/ plic/ ity
two/ fold/ 名词字尾
The ticket agent sold the same ticket to five different customers, this is a clear case of duplicity.
黄牛把同一张票卖给了五个客人，这显然是诈欺。