dual

双重的、两种的

She holds dual citizenship and travels with two passports.

她拥有双重国籍，出国时带著两本护照。

两用的、双功能的

This room serves a dual purpose as an office and a guest bedroom.

这个房间兼作办公室和客房，具有两用功能。

双的、成对的

The car has dual airbags on the driver's side.

这辆车在驾驶座一侧装有双气囊。

双数语法

Ancient Greek had a dual as well as a singular and a plural.

古希腊文除了单数和复数之外还有双数。