1. [词海垂钓]从词典中“钓”出一串同根词吧。
ex-（=out）
2. [词义辨析]写出下列两组单词的词义。
① discrete a.
discreet a.
② secretory a.
secretary n.
3. [同义相连]将左栏的单词和右栏中相对应的词义连接起来。
① indiscernible a.不明智的
② indiscreet b.觉察不出的
③ indiscrete c.不慎重；轻率
④ indiscretion d.不分开的；紧凑的
⑤ unconcerned e.漠不关心的
4. [寻根问底]指出下列单词的词根并领会其词义的由来。
① decree n.法令；政令
decretal a.法令的
② supersecret a.绝密的
③ unconcern n.漠不关心；冷漠
④ undersecretary n.次长，次官，副部长
⑤ incretion n. [医] 内分泌；内分泌物
15. cid, cis [L]=to cut切
cid和cis是一对同源异形根，来自拉丁动词caedere，意为to cut（切）。cid是不定式词干，cis是动名词词干。
decide [de-=away离；cid=to cut切；-e→“to cut away切掉”→“to cut short and bring an end to something裁断某事使之告结”→] v. settle bygiving judgement裁决；决定：The question has been decided.问题已经解决。
▽decidable [decid(e);-able a.] a.可以决定的；解决得了的
decision [decide的对应名词：decis=to decide决定；-ion n.=the act or result表行为或结果→] n. the act or result of deciding决定：The matter is coming to a decision.事情就要定下来了。
▽decisive [decide的对应形容词] a.决定性的；果断的
concise [con-(-com)=thoroughly彻底地；cis=to cut切；-e→“being cut off the unnecessary parts切去不必要的部分”→] a. cut short;brief简洁的；简明的：Write a concise summary of the book.写出这本书的内容简要。
▽concision [concis(e);-ion n.] n.简明性；简洁性
precise [pre-=beforehand事先；cis=to cut切；-e→“being cut off vague-ness beforehand事先已切除含糊的东西的”→] a. clear-cut;accurate明确的；精确的：Be more precise in your answer.回答得更明确些。
▽precision [precis(e);-ion n.] n.精确性；精密度
excide [ex-=out, away出，去；cid=to cut切；-e→] v. cut out;cut away from切开；切除：The surgeon excided the carbuncle with great skill.外科医生熟练地切除了痈疽。
▽excision [ex-;cis;-ion n.] n.切除；删除
incise [in-=into入；cis=to cut切；-e-→] v.① cut into切入，切开：to incise a can with a knife用小刀打开罐头盒② engrave雕刻：to incise a bust雕刻半身像
▽incision [incis(e);-ion n.] n.切入；切开；雕刻
incisure [incis(e);-ure n.] n.切口；刀痕
incisive [in-=into入；cis=to cut切；-ive a.=like像……的→“like cutting into像刀切进去一般”→] a. cutting;sharp or keen锐利的；透彻的：incisive criticisms尖锐的批评
由cid生成的后缀-cide表示killing（杀）或者killer（杀……者）。
homicide [hom=man人；-i-;cide n.=killing, killer杀，杀……者→] n.① killing of man杀人② killer of man杀人者
▽homicidal [homicid(e);-al a.] a.杀人的
suicide [sui=oneself 自己；-cide n.=killing, killer 杀，杀……者→“killing or killer of oneself杀自己（者）”→] I n.① killing of onesel自杀行为：to commit suicide自杀②one who kills himself intentionall自杀者→Ⅱv. kill oneself自杀：He was forced to suicide.他被迫自杀。
▽suicical [suicid(e) n.;-al a.] a.自杀的
bactericide [bacteri=bacteria细菌；-cide n.=killer杀……剂] n. killer of bacteria杀菌剂
▽bactericidal [bactericid(e);-al a.] a.杀菌的
