1. [词根辨识]
分析repetition和动词repeat的关系。那么，词根pet与peat又是什么关系呢？
2. [望文生义]根据所学词根的知识推测下列单词的词义。
① incompetent a.
② inappetence n.
3. [由此及彼]根据已知单词的词义推断出其同根词的词义。
① competitor n.竞争者→competitress n.
② centrifugal a.离心的→centripetal n.
4. [寻根问底]指出下列单词的词根并领会其词义的由来。
① perpetual a.永存的
② perpetuity n.永存（提示：per-=through）
70. ple(t), plen [L]=to fill;full装满（的）
常用词complement，complete和plenty之间有同根关系。词根ple来自拉丁动词plere的不定式词干，plet是它的过去分词pletum的词干，意为to fill（充满）；plen是同源的拉丁形容词plenus的词干部分，意为full（充满的），因为同源近义，把它们放在一起介绍。
complement [com- = together 一起；ple = to fill 装满；-ment n. = the means表手段→“the means of filling together一起填满的手段”→]Ⅰn. something that completes or makes perfect补充，补充物：Travel is an excellent complement to education.旅行能弥补学识之不足。→Ⅱv. form a complement to补足，补充：Reading and writing complement each other.读与写相辅相成。
▽complementary [complement;-ary n.] n.（互为）补充的
supplement [sup-(sub-）=from under自下；ple=to fill装满；-ment n.=the act or result表行为或结果→“the act or result of filling from under自下而上装满的行为或结果”→]Ⅰn. something added to complete or reinforce填补物，增补物：a supplement to an encyclopedia百科全书的补编→Ⅱv. complete or extend by a supplement增补；补充：He supplements his income by sparetime work.他靠业余打工补充收入。
▽supplementary [supplement;-ary a.] a.增补的；追加
complete [com-=together一起；plet =to fill装满；-e→“to fill together一起装满，不留余地的”→]Ⅰa.① having all parts;lacking nothing全部的；完整的：a complete set of Shakespeare's plays整套莎士比亚戏剧集② finished完成的：My homework is complete.我的作业做完了。→Ⅱv. finish完成：to complete an assignment完成任务
▽completist [complet(e) a.;-ist n.] n.求全主义者
completive [complet(e) v.;-ive a.] a.起完全作用的；完成的
deplete [de-=to undo取消；plet=to fill装满；-e→“to undo that of filling取消装满的东西”→] v. use up the supply of;decrease badly耗尽；大大减少：The drought depleted our water supply.干旱耗尽了我们的水源。
▽depletion [deplet(e);-ion n.] n.耗尽；枯竭
replete [re-=again再；plet=to fill装满；-e→“to fill again and again不断装满的”→] a. fully supplied充满的，充实的：a speech replete with humor幽默十足的讲演
plenty [plen=fill充满的；-ty n.=the state表状态→“the state of being full充满的状态”→] n. full amount;abundance充分；丰富：resources in plenty丰富的资源
▽plentiful [plent(y);-i-;-ful a.] a.丰富的；充足的
replenish [re-=again再；plen=full充满的；-ish v.=to make使……→] v. make full again;fill again把……再装满，再备足：to replenish the refrigerator with food把空冰箱再装满食物
▽replenisher [replenish;-er n.] n.补充物；补偿物
