inflammable

[adj] 易燃的性情暴躁的
[n] 易燃物
inflammation [n]  炎症

culprit  = criminal [n] 罪魁祸首
insomnia [n] 失眠
Those who consumed more caffeine tended to have lower levels of inflammation--the culprit behind a number of chronic diseases associated with aging,including certain cancers,joint disorders and even Alzheimer's. 
那些使用更多咖啡因的人往往炎症水平较低，炎症是大多数和年龄相关的慢性病比如说癌症关节失调甚至是阿尔兹海默症罪魁祸首.

tangle

[v] 乱成一团，和...发生争执
intangible [adj] 抽象的，无形的

penetrate [ˈpenɪˌtreɪt]

[v] 进入，渗透，洞察，了解。
prnetration [n] 进入，穿透，渗透，占有率。
penetrative [adj] 有洞察力的，有穿透力的

penetrative observartion 深刻的调查
penetrative criticism/gaze/voice/cold 一针见血的

hover

[v] soar in the sky 空中盘旋
linger [v] 徘徊,逗留 
drift [v] 漂流 

hang over sth/sb 不愉快的事情在心中萦绕  = haunt