1.efficacy n.功效，效力(the capacity or power to produce an effect)

例：Patients' ages may affect a treatment's efficacy.

同根词：efficient(a．有效率的)

2.efficiency n.效率，功效(the quality or degree of being efficient)

词根记忆：来自efficient(a．有效率的)

例：production efficiency生产效率

派生词:inefficiency(n.无效率;无能)

3.efficient a．有效率的(being or involving the immediate agent in producing an effect)；有能力的(competent)

联想记忆：ef（姨夫）+fici(做事)+ent(形容词后缀)--姨夫做事很有效率--有效率的

例：Automobiles become less fuel efficient and therefore contribute more to air pollution as they age.

派生词：efficiently(ad.有效地；高效地)

同根词：efficacy(n.功效，效力)

4.effigy n.雕像,肖像(an image or representation especially of a person)

词根记忆：ef(出)+fig(塑造)+y--塑造出外形--雕像

例：The objects found in the excavated temple were small terracotta(赤土陶器的)effigies.

同根词：figment(n.虚构的事)；figure(n.形体)

5.effluent n.支流（an outflowing branch of a main stream or lake）；废水(waste liquid)

词根记忆：ef（出）+仙(流)+ent--流出来的--支流

例：The factory generates the largest quantities of effluents.

6.egalitarianism n.平等主义(a belief in human equality especially with respect to social, political, and economic rights and privileges)

词根记忆：来自egalitarian(a.平等主义的)

例：racial egalitarianism种族平等主义

7.egoistic a.自我主义的，利己主义的(believing that individual self-interest is the actual motive of all conscious action)

词根记忆：ego(我)+istic--以我为中心的--自我主义的

例：The youth tend to translate the indMdualistic and humanistic goals of democracy into egoistic and materialistic ones.

8.eject v.喷射;驱逐(to throw out)

词根记忆：e（出）+ject(扔)--被扔出来--喷射

例：A meteor stream is composed of dust particles that have been ejected from a parent comet.

派生词：ejection(n.喷出，喷射)

9.elaborate a.精心制作的(planned or carried out with great care)v.详述，详细制定(to work out in detail)

联想记忆：e（出）+labor(工作)+ate--辛苦劳动做出来--精心制作

例：The first paragraph introduces a general thesis that is elaborated on in detail elsewhere in the passage.

派生词：elaborately(ad.苦心经营地，精巧地)

10.elective n.先修课(an elective course or subject)；a.选修的(optional)

词根记忆：e（出）+lect(选择)+ive--选择出--选修课

例：Home economics is only an elective, and few students choose to take it.//elective course选修课