汉：intra 意为“within”，来源于拉丁语，与intra意思相反的前缀是extra。前缀intro来源于拉丁语，意为“into ,inward”，反义前缀是extro。
英:
intra-
word-forming element meaning "within, inside, on the inside," from L. intra "on the inside, within," related to inter "between," from PIE *en-t(e)ro-, from root *en "in" (see in). Commonly opposed to extra-, but the use of intra as a prefix was rare in classical Latin.
intro-
word-forming element, from L. intro "on the inside, within, to the inside," from PIE *en-t(e)ro-, suffixed form of preposition *en "in" (see in). 1.inracontinental
adj.within the continent 大陆的 *intra(=within),con(=together),tin(=hold)
例句：Several intracontinental telephone cables have been laid since them.从那以后，几条大陆间的电话电缆得以铺设。
2.intramural
adj.occurring within the walls or confines of one place,such as a city,organization,school,etc.机构内部的；（尤其指）学校内的，大学内的 *intra(=within),mur(=wall)
例句：Intramural games are played betweeen the students of the same school.校内比赛在同一所学校的学生之间展开。
3.intrastate
adj.within state 州内的 *intra（=within),st(=stand)
例句：A commission was set up in 1976 to regulate intrastate bank mergers.在1976年专门设立了一个委员会来管理州内银行的合并。
4.intravenous
adj.inside a vein 静脉内的 *intra(=vithin),ven(=vein)
例句：Mr.jackson has refused food and won't allow intravenous feeding either.杰克逊先生不但绝食，而且也拒绝通过静脉注射进食。
5.introspective
adj.seeing inwardly 内省的 *intro(=inward),spect(=look)
例句：The series of mishaps has forced South koreans to take an introspective look at their society.一系列的不幸事件促使韩国人开始内省自身的社会问题。
6.introvert
n. one who is more interested in his own thoughts and feelings than in things outside himself 性格内向的人 *into (=inward),vert(=trun)
例句：Harris is a shy introvert so imagine our surprise when he volunteered to speak.哈理期是一个非常害羞的内向的人，所以你可以想象当地主动请求发言时，我们多么惊讶。