四联的英文：
quad
n.
1. = quadrangle 四方院子（四周有建筑，常见于校园）
2. = quadruplet 四胞胎之一
quad bistable latch
四组双稳锁存器
The front quad, where I lived, was floored and tented.
在我居住的四方院子的前排楼房下已经铺起地板，支起帐篷。
Downhill running has its upsides but kills your quads. Here's how to avoid the burn.
下坡跑有好处，但是容易伤着您的股四头肌。以下是如何避免这种伤害。
They called themselves the quad squad--whose kindness and cheer-fulness supported me during those nerve-racking weeks.
他们管自己叫四胞胎工作队。在那使人神经紧张的几个星期里，是他们的善待和乐观精神支持了我。