词根词缀：fac-, facil-, fact-, feas-, -feat, -fect, -feit, -facient, -faction, -fic-, -fy, -ficate, -fication

【来源及含义】Latin: to make, to do, to build, to cause, to produce; forming, shaping

【同源单词】Ab officio et beneficio, abortifacient, absorbefacient, absorbifacient, acoustoelectric effect, affair

词根词缀：rar-, rare-

【来源及含义】Latin: rarus, rare, thin, loose, sparse; airy, porous, infrequent, unusual

【同源单词】bone rarefaction, rare, rare species, rare, rare-earth alloy, rare-earth elements