1.sentinel n．哨兵(sentry)
词根记忆：senti(感觉)+nel--感觉者--哨兵
注意：sentry(n．哨兵)
例；The sentinel was stationed on a hill.
2.separate a．分开的(detached)；单个的(individual)；不同的(distinct, dissimilar);v.(from)分开(distinguish)；分类(sort)
词根记忆：se（分开）+par(相等)+ate--（使）分成份--分开
例：Restaurants of the city can maintain separate dining areas where smoking is permitted.//Residents should separate recyclable bottles are cans from recyclable paper products.
派生词：separately( ad.个别地：分离地)：separation(n.分离)
3.sequence n.顺序(an order of succession)；序列(an ordered set of quantities)
词根记忆：sequ(跟随)+ence--跟随，连续--序列
例：New techniques for determining the molecular sequence of the RNA have produced evolutionary information.//arithmetic sequence数列
派生词：sequential(a．连续的；一连串的)
4.sequester v.（使）隐退(to seclude; withdraw);使隔离(to set apart)
注意不要和sequestrate(v.扣押)相混
例：As recently as 1950, tuberculosis was never curable unless patients were sequestered in sanitariums; today, the drug Isoniazid has made such treatment obsolete.
派生词：sequestered（a．隐退的：偏僻的）
5.session n．会议(conference)：集会（a meeting devoted to a particular activity）
例：regular session常规会议//an all-night dancing session通宵舞会
6.severe a．严重的(serious)；严厉的(austere)；严酷的(harsh)
联想记忆：曾经(ever)严酷的(severe)日子，一去不复返了
例：Most countries in the world have severe air pollution.//The angry parents gave the naughty child a severe punishment.
派生词：severely( ad.严格地；严重地)；severity(n．严重；剧烈)
7.sewage n.污物，污水(refuse liquids or waste matter usually carried off by sewers)
词根记忆：sew(排水)+age--排出的水--污水
派生词：sewage disposal污水处理
8.shareholder n．股票持有人；股东(stockholder)
分拆记忆：share(分享；股票)+holder(持有者)--股票持有人
例：The individual shareholder will reap only a minute share of the gains.
派生词：shareholding(n．股权)
9.shatter v.粉碎，砸碎(to break into pieces)；破坏（to destroy; demolish）
记：与scatter(v.分散)一起记
例：The sea dashed the ship to shatter against the rock.//Heating could shatter the nutrition of food.