前缀 sub- 含义为 under
其变形有suc-, suf-, sug-, sum-, sup-, sur-, sus-等。（其中c,f,g,m,p,r,s为辅音字母前的变形，比如suggestion为 sug- gestion)
当它作为介词性前缀与名词结合时，可能改变词基单词的词性。
具体示例有，
1.submissive [(sub( =under) +miss( =send)把自己向下派送]
adj. be～to yielding to the control or authority of another; meek 服从的，顺从的；柔顺的，温顺的 submit 服从，投降，屈服；提交 submission 服从，投降
ex) Rather than being submissive or aggressive, it's healthier to be assertive.
比起顺从或挑衅，坚持己见要更有益于身心。
2.subordinate [(sub( =under) +ordin( =order)在下面接受命令]
adj. be～to inferior to or placed below another in rank, power, importance, etc. 地位、阶级等低的；下级的；从属的
n. person in a subordinate position 下级，从属者，部下
vt. place in a subordinate position 把…列入下级，使从属
subordination 下级，从属 subordinative 从属的
ex) If you speak to my subordinate, he can get the answer for you.
如果你跟我的下属讲，他会给你一个答复的。
3.subsequent [(sub( =under) +sequ（=follow）在下面（尾部）接着发生]
adj. be～to coming after; following in time, place, or order 后续的；以后的
subsequently 此后，其后，随后 subsequence 后继
ex) Subsequent tests revealed that she was suffering from pleurisy.
接下来的检查结果证明她患了胸膜炎。
4.suffrage [(suf<sub( =under) +frag( =break, loud applause)称赞到底]
n. franchise, right of voting in political elections; vote, consent expressed by voting 授票权，选举权；投票；赞成票
ex) Suffrage is constitutionally guaranteed to all non-criminal adults.
宪法保障所有不违法的成年人都有选举权。
5.supplement [sup<sub( =under) +ple（=fill）在下面填满]
vt. sth+with+sth make up for a lack or deficiency 补充
n. something added 补充，增补；附录，增刊
supplementary 补充的，追加的；补角的
ex) Most breakfast cereals contain a host of vitamin and mineral supplements.
大部分的早餐谷类食品中都含有大量的维生素和矿物质添加剂。
6.substantial [sub( =under) +st( =stand)站在下面]
adj. virtual; having physical existence; essential; solidly or strongly built or made;large; ample; considerable; well-to-do 实质的，本质上的；健壮的，结实的；大量的，丰富的，丰足的；富裕的
substantiate 证实；使实体化 substance 物质：本质；要旨；坚固；财产
substantive 独立的；实际的
ex) He promised me a substantial salary raise around the first of the yerar.
他答应我，年初左右会给我大幅度提升薪水。
7.sustain [sus<sub( =under) +tain( =hold)在下面支撑]
vt. keep from falling or sinking; keep up; maintain; suffer, undergo; support;
uphold-admit 支撑；维持；遭受、蒙受损失等；经历，承受：供养，维持（生命等）；确认；认可 sustenance 生计；食品，营养品；维持
ex) During the lean years, egg sales alone sustained our farm.
赶上灾年，我们只能靠卖鸡蛋来维持农场的生计。
8.subjugate [sub (=under) +jug (=bind, join)在下面捆]
vt. bring under control or subjection; conquer 使服从；使从属；征服
subjugation 从属；征服
ex) Rapists subjugate women not only physically but also emotionally.
强奸犯不仅从身体上而且从情绪上迫使女性屈从。
9.succumb [suc<sub( =under) +cumb( =lean．lie)向下屈身]
vt. to+sth give way to; yield to temptation, flattery, etc.; die 屈服，屈从于；死
ex) He succumbed to malaria after several long nights of chills and fevers.
经受了几夜的风寒和高烧，他最终死于疟疾。
10.supplant [sup<sub( =under,in place of) +plant( =plant)取代某物栽种]
vt. take the place of; take the place of someone, especially after getting him out of office 取代；把…排挤掉 supplanter 取而代之的人
ex) Lasers supplanted the use of scalpels for eye surgery decades ago.
激光替代了几十年前眼科手术中使用的解剖刀。
详细介绍：
前缀sub-来源拉介词sub,意为“under,from under”等，表示“在下”的位置或“自下而上”的运动。作为原生前缀，sub-出现在许多12世纪后引进的拉丁借词中，sub-依然遵守拉丁读音规则，接受词根首字母的同化产生出suc-,suf-,sug-,sum-,sup-,sur-,sus-,su-等变形异体。但在16世纪以后，sub-可作为活性派生词缀与各种语源的单词结合构成新词。在这些派生词中，sub-没有异体，而意思却有所引申。除under之外，它还可以表示“secondary, slightly,in place of, precisely"等含义。派生前缀sub-可以与名词、形容词、动词等结合。当他作为介词性前缀与名词结合时，可能改变词基单词的词性。与包含sub- 的拉丁借词相比，由派生前缀sub- 构成单词数量更多。
来源：
词根词源字典 www.etymon.cn
