汉： 前缀tri-来源于拉丁语，意为“three”表示“三”，关于数字“三”的这个前缀，有的书上也把它当作词根来记，可以看一下从数字三开始了解英词汇记忆的奥秘这篇文章。tri与three之间发生元音音变，和"h"的弱化，由three变成了tri.
英：word-forming element meaning "three," from L. tres (neuter tria) or Gk. treis (neuter tria) "three" (see three).
1.tricycle
n.three-wheeled bicycle 三轮车 cycl=wheel
Tricycle were much more common than bicycles in the 1800's
在19世纪，三轮车比自行车常见的多 2.tripod
n.three-legged support,eg,for acamera;stool,table,etc.resisting on three legs 照相机等的三脚架；三脚桌，tri=three,pod=foot
Set the camera on a tripod so there is no shaking during exposure.
把照相机放在三脚架上，可防止曝光时相机抖动。
3.trisect
v.divide a line,an angle etc,into three parts 三（等）分
sect=cut tri=three
We trisected the pie,one section for each of the three of us.
我们平均把馅饼分成了三分，每人一份。