brighten：(使)发光，(使)发亮；(使)快活，(使)活跃

词根词缀：bright发光的 + -en动词词尾,使变成…

• subsidiary
• subsidize
• subsidy
• subsist
• subsistence
• subsoil
• subsonic
• substance
• substandard
• substantial
• substantiate
• substantive
• substation
• substitute
• substitution
• substrate
• substratum
• substructure
• subsume
• subtend
• subterfuge
• subterranean
• subtext
• subtility
• subtitle